Initial copy stand design

.gitignore

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+__pycache__/
+*.py[cod]
+core
+core.*

README.md

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+# Copy Stand Base Plate
+
+A parametric, 3D-printed copy-stand base sized for a Bambu Lab X2D and designed
+around a Lobster Holder V2.1 on its CS-Lite. The base uses a removable 2020
+extrusion socket, adjustable 1/4-20 feet, and an optical-breadboard-style
+1-inch grid of heat-set inserts.
+
+The structural parts are intended for black ASA. Grid lines are flush blue ASA
+inlays printed against a textured build plate.
+
+## Coordinate system and principal dimensions
+
+- Base: 203.2 x 248 x 15 mm, with 12.7 mm corner radii.
+- The grid origin is Y=0 and positive Y runs toward the operator. The socket's
+  straight front reference face is Y=12.7 mm (0.5 inch), halfway between the
+  origin and the first insert row.
+- The 8 x 8 insert array has 25.4 mm spacing. Its rows are Y=25.4 through
+  Y=203.2 mm relative to the socket datum.
+- A blue Y=0 datum line continues beneath the socket, leaving aligned visible
+  segments on both sides.
+- The removable socket captures 50 mm of a nominal 20 x 20 mm extrusion.
+- Its 110 x 38.7 x 10 mm flange reaches from the rear plate edge to the
+  half-inch reference face. The column is shifted forward to improve the
+  overturning load path and reduce the camera arm's required overhang.
+- The two outside inserts in the front grid row also mount the front leveling
+  feet. They cannot accept top-side accessories while the feet are installed.
+
+## Hardware
+
+| Qty | Item | Relevant dimensions |
+| ---: | --- | --- |
+| 70 | [McMaster 97171A240 brass 1/4-20 heat-set insert](https://www.mcmaster.com/97171A240/) | 9.525 mm body, 12.7 mm flange, 1.27 mm flange thickness, 8.026 mm maximum hole |
+| 4 | [1/4-20 adjustable foot](https://www.amazon.com/dp/B095PDSNPM) | 19 mm pad diameter, 8.5 mm pad height, 17.8 mm stud |
+| 4 | [Knurled 1/4-20 locking nut](https://www.amazon.com/dp/B0GQSX98V4) | 24.4 mm OD, 6 mm thick |
+| 1 | [European-style 2020 T-slot extrusion](https://www.amazon.com/dp/B08Y8N7FD1) | 20 x 20 x 400 mm, 6 mm slots |
+| 4 | 1/4-20 x 1-inch socket-head screws | Socket flange to base |
+| 4 | Black 1/4-inch flat washers, specified as 0.7 inch (17.78 mm) OD | Load distribution beneath socket screw heads; measure thickness before assembly |
+| 4 | M5 x 10 mm socket-head screws and European 2020 T-nuts | Extrusion clamp; verify screw length against the selected T-nut |
+
+The four feet use four of the listed inserts: two dedicated rear inserts and
+the two shared front grid inserts. Four more dedicated inserts secure the
+socket. The remaining 64 inserts make up the complete grid.
+
+The McMaster drawing requires at least 0.530 inch (13.46 mm) of material. Every
+insert boss in this design is 15 mm tall, including all four socket-mounting
+bosses. The 52.5 x 22.5 mm locating slot passes through the base between those
+bosses, so it does not reduce their thickness. Inserts install from the open
+underside with their flange flush against the boss. The 1.35 mm flange seat and
+9.525 mm body leave a 4.125 mm screw-clearance tunnel below the clean 6.8 mm
+opening in the working surface.
+
+## Build
+
+Requirements: OpenSCAD 2021.01 or later, Ruby, and Python 3.
+
+```bash
+ruby build.rb
+```
+
+The build is incremental. Run `REBUILD=1 ruby build.rb` to regenerate every
+component after changing geometry parameters.
+
+Generated files are placed under `exports/3mf` and `exports/stl`. The primary
+files are:
+
+- `base_multicolor.3mf`: aligned black base and blue inlay meshes, assigned to
+  filaments 1 and 2.
+- `socket.3mf`: removable black socket and gusset assembly.
+- `coupon_multicolor.3mf`: two-piece insert, rail-clearance, through-key-fit,
+  and line calibration coupon.
+- `coupon_key.3mf`: standalone full-size tongue gauge from the two-piece
+  coupon.
+
+The portable multipart files intentionally do not embed a printer or process
+profile. The individual aligned meshes and single-color fallbacks are retained
+alongside them.
+
+## Calibrate before the full base
+
+Print `coupon_multicolor.3mf` in the intended ASA, face down on the intended
+textured plate. It produces a main coupon and a separate full-size tongue
+gauge. From left to right, the insert pilots are 7.70, 7.85, 8.00, 8.15, and
+8.30 mm. The four rail gauges are 20.0, 20.1, 20.2, and 20.3 mm. Each is a
+four-wall collar with the production 6 mm side walls, 2.7 mm end walls, and
+full 50 mm engagement depth. External gussets and M5 holes are omitted because
+they do not define the rail-fit surfaces. The coupon also
+contains the production-width blue line and a 6 mm-deep production-size
+52.5 x 22.5 mm through-slot. The separate 52 x 22 x 6 mm tongue prints in the
+same orientation as the socket tongue and has a support-free stop shoulder and
+vertical grip for insertion and removal. Verify that the slot is visibly open,
+with no first-layer membrane, before testing the fit.
+
+The production model defaults to the physically calibrated 8.10 mm insert
+pilot and 20.1 mm rail cavity. These values were selected from an ASA coupon:
+the 20.1 mm collar accepted the fully cooled rail through all 50 mm by hand
+without objectionable play, and the 8.10 mm pilot provided the preferred
+insert fit. The rectangular tongue and through-slot also passed the physical
+fit test, so their dimensions remain unchanged. For another printer, material,
+or process, select the smallest rail gauge that fits without forcing and use
+the insert pilot that gives the required installation grip. Change
+`insert_pilot_diameter` or `rail_clearance` at the top of `copy_stand.scad`,
+then rebuild. The 8.30 mm coupon remains a diagnostic oversize option;
+McMaster specifies 8.026 mm as the maximum nominal hole diameter, while this
+design's 8.10 mm production value reflects the tested print process.
+
+## Bambu Studio setup
+
+1. Open `base_multicolor.3mf` as one multipart object.
+2. Assign black ASA to Filament 1 and blue ASA to Filament 2.
+3. Keep the 248 mm dimension along the printer's Y axis and place the base to
+   one side. Its 203.2 mm X width leaves about 52.8 mm for a nominal 35 x 35 mm
+   prime tower and clearance.
+4. Confirm the tower and any brim fit in Preview before printing.
+5. Print the base face down. No support is designed into the base, socket, or
+   coupon.
+
+The coupon occupies approximately 228 x 110 x 53.2 mm including its separate
+tongue and full-depth rail collars. Orient its 228 mm dimension along Y to
+leave ample X space for the prime tower.
+
+A 0.4 mm nozzle and 0.20 mm layers are the compatibility target. Use at least
+six walls, six top and bottom layers, and 40-50% gyroid or cubic infill for the
+socket. Use at least four walls for the base, suitable ASA bed adhesion, a
+fully heat-soaked enclosure, and conservative cooling. The modeled open cells
+provide the base structure; sparse slicer infill is not relied on there.
+
+## Assembly
+
+1. Heat-set the inserts from the underside. Stop when each brass flange is
+   flush with its counterbore; do not pull it toward the textured top surface.
+2. Thread the leveling feet through their locking nuts and into the two rear
+   foot inserts and two outer inserts of the front grid row.
+3. Lower the socket's 52 x 22 x 6 mm tongue into the base's through-slot, then
+   fasten the flange with four 0.7-inch OD washers and four 1/4-20 x 1-inch
+   screws. The screws provide clamping and vertical retention; the tongue
+   provides repeatable X/Y location and carries lateral shear. With a washer
+   thickness `t` in millimeters, nominal insert engagement is
+   `11.275 - t` mm, limited by the insert's 9.525 mm threaded length.
+4. Preload two T-nuts in each side slot of the extrusion. Lower the extrusion
+   to the socket floor and fasten it through the four M5 clamp holes.
+5. Level the base, then tighten each knurled locking nut against its insert
+   flange.
+
+The Lobster/CS-Lite locating fixture, Arca rail, camera carriage, and camera
+alignment accessories are deliberately deferred. They can attach to the grid
+without changing this base.
+
+The socket's broad side buttresses stop before the four base screws. Vertical
+19 mm washer and tool envelopes preserve access above those screws, and 14 mm
+horizontal tunnels provide driver access to the M5 rail clamps without
+sacrificing the collar wall around the T-slot extrusion. The 19 mm fore/aft
+screw-row spacing and shallower side buttresses improve overturning and
+torsional resistance compared with the compact first revision.
+
+Before mounting a camera, proof-test the assembled stand with a dummy load at
+the maximum working overhang. Under the normal payload, target less than 1 mm
+of rail-tip motion. After 24 hours at twice the intended payload, require no
+cracking, washer embedment, or loose fasteners and less than 0.25 mm permanent
+rail-tip displacement after unloading.

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build.rb

@@ -0,0 +1,90 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require "fileutils"
+require "open3"
+
+ROOT = File.expand_path(__dir__)
+SCAD = File.join(ROOT, "copy_stand.scad")
+OPENSCAD = ENV.fetch("OPENSCAD", "openscad")
+PYTHON = ENV.fetch("PYTHON", "python3")
+EXPORT_3MF = File.join(ROOT, "exports", "3mf")
+EXPORT_STL = File.join(ROOT, "exports", "stl")
+COMPONENT_3MF = File.join(EXPORT_3MF, "components")
+COMPONENT_STL = File.join(EXPORT_STL, "components")
+
+def run!(*command)
+  puts command.join(" ")
+  output, status = Open3.capture2e(*command)
+  puts output unless output.empty?
+  raise "Command failed: #{command.join(' ')}" unless status.success?
+end
+
+def export(part, directory, extension)
+  output = File.join(directory, "#{part}.#{extension}")
+  return output if ENV["REBUILD"] != "1" && File.size?(output)
+
+  run!(OPENSCAD, "-o", output, "-D", %(part="#{part}"), SCAD)
+  output
+end
+
+def export_segment(part, index, directory, extension)
+  output = File.join(directory, "#{part}_#{index}.#{extension}")
+  return output if ENV["REBUILD"] != "1" && File.size?(output)
+
+  run!(OPENSCAD, "-o", output, "-D", %(part="#{part}"),
+       "-D", "segment_index=#{index}", SCAD)
+  output
+end
+
+def package(output, title, bases, accents = [])
+  command = [
+    PYTHON, File.join(ROOT, "tools", "package_multimaterial_3mf.py"),
+    output, "--title", title
+  ]
+  bases.each { |path| command.concat(["--base", path]) }
+  accents.each { |path| command.concat(["--accent", path]) }
+  run!(*command)
+end
+
+FileUtils.mkdir_p([EXPORT_3MF, EXPORT_STL, COMPONENT_3MF, COMPONENT_STL])
+
+%w[base_accent socket coupon coupon_black coupon_key coupon_accent].each do |part|
+  export(part, EXPORT_3MF, "3mf")
+end
+
+%w[socket coupon coupon_key].each do |part|
+  export(part, EXPORT_STL, "stl")
+end
+
+base_segments = (0..5).map do |index|
+  export_segment("base_segment", index, COMPONENT_3MF, "3mf")
+end
+black_segments = (0..5).map do |index|
+  export_segment("base_black_segment", index, COMPONENT_3MF, "3mf")
+end
+
+package(File.join(EXPORT_3MF, "base.3mf"), "Copy Stand Base - Single Color",
+        base_segments)
+package(File.join(EXPORT_3MF, "base_black.3mf"), "Copy Stand Base - Black Mesh",
+        black_segments)
+package(File.join(EXPORT_3MF, "base_multicolor.3mf"), "Copy Stand Base",
+        black_segments, [File.join(EXPORT_3MF, "base_accent.3mf")])
+
+package(File.join(EXPORT_3MF, "coupon_multicolor.3mf"),
+        "Copy Stand Calibration Coupon",
+        [File.join(EXPORT_3MF, "coupon_black.3mf"),
+         File.join(EXPORT_3MF, "coupon_key.3mf")],
+        [File.join(EXPORT_3MF, "coupon_accent.3mf")])
+
+# A multi-solid ASCII STL fallback avoids forcing OpenSCAD/CGAL to union the
+# large stepped base in one expensive operation. Slicers merge the touching
+# solids at slice time.
+segment_stls = (0..5).map do |index|
+  export_segment("base_segment", index, COMPONENT_STL, "stl")
+end
+File.open(File.join(EXPORT_STL, "base.stl"), "wb") do |combined|
+  segment_stls.each { |path| combined.write(File.binread(path)) }
+end
+
+puts "Exports written to #{File.join(ROOT, 'exports')}"

copy_stand.scad

@@ -0,0 +1,628 @@
+/*
+ * Parametric copy-stand base for a Bambu Lab X2D.
+ * Service coordinates: X left-to-right, Y rear-to-front, Z bottom-to-top.
+ * The grid origin is at plate Y=datum_y. The socket's straight front edge is
+ * 0.5 inch forward of that origin and remains a convenient reference face.
+ */
+
+/* [Output] */
+part = "assembly"; // [assembly,base,base_black,base_segment,base_black_segment,base_accent,socket,coupon,coupon_black,coupon_key,coupon_accent]
+segment_index = 0; // [0:1:5]
+show_references = true;
+
+/* [Base] */
+plate_width = 203.2;
+plate_depth = 248;
+plate_height = 15;
+corner_radius = 12.7;
+datum_y = 26;
+top_skin = 3.2;
+perimeter_wall = 3.2;
+rib_width = 2.4;
+
+/* [Grid inlay] */
+grid_pitch = 25.4;
+grid_columns = 8;
+grid_rows = 8;
+grid_line_width = 0.8;
+inlay_depth = 0.6;
+inlay_clearance = 0.08;
+
+/* [McMaster 97171A240 inserts] */
+insert_pilot_diameter = 8.1;
+insert_body_length = 9.525;
+insert_flange_diameter = 12.9;
+insert_flange_depth = 1.35;
+screw_clearance_diameter = 6.8;
+insert_boss_diameter = 20;
+
+/* [Feet] */
+foot_pad_diameter = 19;
+foot_pad_height = 8.5;
+foot_stud_length = 17.8;
+foot_nut_diameter = 24.4;
+foot_nut_height = 6;
+
+/* [Removable 2020 socket] */
+rail_size = 20;
+rail_clearance = 0.05;
+socket_capture = 50;
+socket_front_y = grid_pitch / 2;
+socket_rear_y = -datum_y;
+socket_flange_size = [110, socket_front_y - socket_rear_y, 10];
+socket_key_size = [52, 22, 6];
+socket_key_clearance = 0.25;
+socket_side_wall = 6;
+socket_end_wall = 2.7;
+socket_mount_x = 45;
+socket_mount_ys = [-16, 3];
+socket_mount_tool_diameter = 19;
+socket_gusset_outer_x = 35;
+socket_gusset_y_span = [-23, 10];
+socket_gusset_height = 32;
+rail_screw_diameter = 5.5;
+rail_screw_head_diameter = 9.5;
+rail_screw_head_depth = 3;
+rail_tool_diameter = 14;
+rail_screw_heights = [15, 40];
+
+/* [Calibration] */
+coupon_insert_diameters = [7.70, 7.85, 8.00, 8.15, 8.30];
+coupon_rail_gaps = [20.0, 20.1, 20.2, 20.3];
+
+$fn = $preview ? 36 : 72;
+eps = 0.02;
+
+assert(plate_width <= 256 && plate_depth <= 256,
+    "Base exceeds the X2D main-nozzle build area");
+assert(plate_height >= 13.462,
+    "Insert bosses violate McMaster's 0.530-inch minimum material thickness");
+assert(top_skin > inlay_depth,
+    "Top skin must be thicker than the inlay");
+assert(grid_columns == 8 && grid_rows == 8,
+    "This release's shared front-foot geometry expects an 8 x 8 grid");
+assert(socket_key_size[0] / 2 + socket_key_clearance
+        < socket_mount_x - insert_boss_diameter / 2,
+    "Socket key slot overlaps a full-depth mounting-insert boss");
+assert(socket_gusset_outer_x
+        < socket_mount_x - socket_mount_tool_diameter / 2,
+    "Socket gusset enters a flange-screw tool-access envelope");
+assert(socket_front_y == grid_pitch / 2,
+    "Socket reference face must remain at the half-inch grid coordinate");
+assert(socket_rear_y == -datum_y,
+    "Socket flange must reach the rear edge of the base");
+assert(socket_mount_x + socket_mount_tool_diameter / 2
+        <= socket_flange_size[0] / 2,
+    "Socket washer envelope exceeds the flange width");
+assert(socket_mount_ys[0] - socket_mount_tool_diameter / 2
+        >= socket_rear_y
+        && socket_mount_ys[len(socket_mount_ys) - 1]
+            + socket_mount_tool_diameter / 2 <= socket_front_y,
+    "Socket washer envelope exceeds the flange depth");
+assert(socket_rail_axis_y() + socket_key_size[1] / 2
+        + socket_key_clearance
+        < grid_pitch - insert_boss_diameter / 2,
+    "Socket key slot overlaps the first grid-row insert bosses");
+assert(socket_mount_ys[len(socket_mount_ys) - 1]
+        + insert_boss_diameter / 2
+        < grid_pitch - insert_boss_diameter / 2,
+    "Socket mounting bosses overlap the first grid-row bosses");
+assert(socket_key_size[2] < plate_height,
+    "Socket tongue must stop above the base underside");
+
+grid_xs = [for (i = [0 : grid_columns - 1])
+    plate_width / 2 + (i - (grid_columns - 1) / 2) * grid_pitch];
+grid_ys = [for (i = [1 : grid_rows]) datum_y + i * grid_pitch];
+rear_foot_ys = corner_radius;
+socket_hole_xs = [plate_width / 2 - socket_mount_x,
+    plate_width / 2 + socket_mount_x];
+socket_hole_ys = [for (y = socket_mount_ys) datum_y + y];
+all_insert_points = concat(
+    [for (x = grid_xs, y = grid_ys) [x, y]],
+    [for (x = [grid_xs[0], grid_xs[len(grid_xs) - 1]]) [x, rear_foot_ys]],
+    [for (x = socket_hole_xs, y = socket_hole_ys) [x, y]]
+);
+
+module rounded_rect_2d(size, radius) {
+    offset(r = radius)
+        square([size[0] - 2 * radius, size[1] - 2 * radius], center = true);
+}
+
+module rounded_prism(size, radius) {
+    linear_extrude(height = size[2])
+        rounded_rect_2d([size[0], size[1]], radius);
+}
+
+module plate_outline_2d(inset = 0) {
+    translate([plate_width / 2, plate_depth / 2])
+        offset(delta = -inset)
+            rounded_rect_2d([plate_width, plate_depth], corner_radius);
+}
+
+module insert_boss_at(x, y) {
+    translate([x, y, 0]) cylinder(h = plate_height, d = insert_boss_diameter);
+}
+
+module insert_positive_bosses() {
+    for (p = all_insert_points) insert_boss_at(p[0], p[1]);
+}
+
+module underside_structure_2d() {
+    intersection() {
+        plate_outline_2d();
+        union() {
+            difference() {
+                plate_outline_2d();
+                plate_outline_2d(perimeter_wall);
+            }
+            for (x = grid_xs)
+                translate([x - rib_width / 2, corner_radius, 0])
+                    square([rib_width, plate_depth - 2 * corner_radius]);
+            for (y = concat([datum_y], grid_ys))
+                translate([corner_radius, y - rib_width / 2, 0])
+                    square([plate_width - 2 * corner_radius, rib_width]);
+
+            translate([corner_radius, rear_foot_ys - rib_width / 2, 0])
+                square([plate_width - 2 * corner_radius, rib_width]);
+            for (x = socket_hole_xs)
+                translate([x - rib_width / 2, corner_radius, 0])
+                    square([rib_width, datum_y - corner_radius]);
+
+            for (p = all_insert_points)
+                translate(p) circle(d = insert_boss_diameter);
+        }
+    }
+}
+
+module base_structure_positive() {
+    union() {
+        linear_extrude(height = plate_height - top_skin)
+            underside_structure_2d();
+        translate([0, 0, plate_height - top_skin])
+            linear_extrude(height = top_skin) plate_outline_2d();
+    }
+}
+
+module one_insert_cutout(x, y, pilot = insert_pilot_diameter) {
+    translate([x, y, -eps])
+        cylinder(h = insert_flange_depth + eps, d = insert_flange_diameter);
+    translate([x, y, insert_flange_depth - eps])
+        cylinder(h = insert_body_length + 2 * eps, d = pilot);
+    translate([x, y, insert_flange_depth + insert_body_length - eps])
+        cylinder(
+            h = plate_height - insert_flange_depth - insert_body_length + 2 * eps,
+            d = screw_clearance_diameter
+        );
+}
+
+module all_insert_cutouts() {
+    union() {
+        for (p = all_insert_points)
+            translate([p[0], p[1], -eps])
+                cylinder(h = insert_flange_depth + eps,
+                    d = insert_flange_diameter);
+    }
+    union() {
+        for (p = all_insert_points)
+            translate([p[0], p[1], insert_flange_depth - eps])
+                cylinder(h = insert_body_length + 2 * eps,
+                    d = insert_pilot_diameter);
+    }
+    union() {
+        for (p = all_insert_points)
+            translate([p[0], p[1],
+                       insert_flange_depth + insert_body_length - eps])
+                cylinder(
+                    h = plate_height - insert_flange_depth
+                        - insert_body_length + 2 * eps,
+                    d = screw_clearance_diameter
+                );
+    }
+}
+
+module insert_pattern_2d(diameter) {
+    for (p = all_insert_points) translate(p) circle(d = diameter);
+}
+
+module socket_key_2d(clearance = 0) {
+    translate([plate_width / 2, datum_y + socket_rail_axis_y()])
+        rounded_rect_2d(
+            [socket_key_size[0] + 2 * clearance,
+             socket_key_size[1] + 2 * clearance],
+            2 + clearance
+        );
+}
+
+module grid_artwork_2d(clearance = 0) {
+    intersection() {
+        plate_outline_2d();
+        offset(delta = clearance)
+            union() {
+                for (x = grid_xs)
+                    translate([x - grid_line_width / 2, datum_y])
+                        square([grid_line_width, plate_depth - datum_y]);
+                for (y = concat([datum_y], grid_ys))
+                    translate([0, y - grid_line_width / 2])
+                        square([plate_width, grid_line_width]);
+            }
+    }
+}
+
+module accent_service() {
+    translate([0, 0, plate_height - inlay_depth])
+        linear_extrude(height = inlay_depth)
+            difference() {
+                grid_artwork_2d();
+                insert_pattern_2d(screw_clearance_diameter);
+                socket_key_2d(socket_key_clearance);
+            }
+}
+
+module base_layer_2d(outline = false, hole_diameter, artwork = false) {
+    difference() {
+        if (outline) plate_outline_2d();
+        else underside_structure_2d();
+        insert_pattern_2d(hole_diameter);
+        // The locator is a through-slot so no unsupported bridge is printed
+        // against the textured build plate.
+        socket_key_2d(socket_key_clearance);
+        if (artwork) grid_artwork_2d(inlay_clearance);
+    }
+}
+
+module base_segment_service(index, with_artwork = false) {
+    underside_top = plate_height - top_skin;
+    body_top = insert_flange_depth + insert_body_length;
+    artwork_bottom = plate_height - inlay_depth;
+    top_split = (underside_top + artwork_bottom) / 2;
+
+    if (index == 0)
+        linear_extrude(height = insert_flange_depth)
+            base_layer_2d(false, insert_flange_diameter);
+    else if (index == 1)
+        translate([0, 0, insert_flange_depth])
+            linear_extrude(height = insert_body_length)
+                base_layer_2d(false, insert_pilot_diameter);
+    else if (index == 2)
+        translate([0, 0, body_top])
+            linear_extrude(height = underside_top - body_top)
+                base_layer_2d(false, screw_clearance_diameter);
+    else if (index == 3)
+        translate([0, 0, underside_top])
+            linear_extrude(height = top_split - underside_top)
+                base_layer_2d(true, screw_clearance_diameter);
+    else if (index == 4)
+        translate([0, 0, top_split])
+            linear_extrude(height = artwork_bottom - top_split)
+                base_layer_2d(true, screw_clearance_diameter);
+    else if (index == 5)
+        translate([0, 0, artwork_bottom])
+            linear_extrude(height = inlay_depth)
+                base_layer_2d(true, screw_clearance_diameter, with_artwork);
+    else assert(false, str("Unknown base segment: ", index));
+}
+
+module base_layered_service(with_artwork = false) {
+    for (i = [0 : 5]) base_segment_service(i, with_artwork);
+}
+
+module base_black_service() {
+    base_layered_service(true);
+}
+
+module base_complete_service() {
+    base_layered_service(false);
+}
+
+module print_orient_base() {
+    translate([0, plate_depth, plate_height])
+        rotate([180, 0, 0]) children();
+}
+
+module socket_flange_2d() {
+    translate([0, (socket_front_y + socket_rear_y) / 2])
+        rounded_rect_2d([socket_flange_size[0], socket_flange_size[1]], 3);
+}
+
+function socket_outer_y() = rail_size + 2 * rail_clearance
+    + 2 * socket_end_wall;
+function socket_rail_axis_y() = socket_front_y - socket_outer_y() / 2;
+
+module socket_key_local_2d() {
+    translate([0, socket_rail_axis_y()])
+        rounded_rect_2d([socket_key_size[0], socket_key_size[1]], 2);
+}
+
+module socket_gusset(side = 1) {
+    cavity = rail_size + 2 * rail_clearance;
+    collar_half_x = (cavity + 2 * socket_side_wall) / 2;
+    near_x = side > 0 ? collar_half_x : -collar_half_x - 2;
+    outer_x = side > 0 ? socket_gusset_outer_x - 2
+        : -socket_gusset_outer_x;
+    gusset_depth = socket_gusset_y_span[1] - socket_gusset_y_span[0];
+
+    // Broad buttress with a short outer reach. Tool-access bores below remove
+    // any material that could obstruct either family of fasteners.
+    hull() {
+        translate([near_x, socket_gusset_y_span[0], socket_flange_size[2]])
+            cube([2, gusset_depth, socket_gusset_height]);
+        translate([outer_x, socket_gusset_y_span[0], socket_flange_size[2]])
+            cube([2, gusset_depth, 2]);
+    }
+}
+
+module socket_positive() {
+    cavity = rail_size + 2 * rail_clearance;
+    outer_x = cavity + 2 * socket_side_wall;
+    outer_y = socket_outer_y();
+
+    translate([0, 0, -socket_key_size[2]])
+        linear_extrude(height = socket_key_size[2] + eps)
+            socket_key_local_2d();
+    linear_extrude(height = socket_flange_size[2]) socket_flange_2d();
+    translate([-outer_x / 2, socket_front_y - outer_y,
+               socket_flange_size[2]])
+        cube([outer_x, outer_y, socket_capture]);
+    socket_gusset(-1);
+    socket_gusset(1);
+}
+
+module socket_cutouts() {
+    cavity = rail_size + 2 * rail_clearance;
+    collar_half_x = (cavity + 2 * socket_side_wall) / 2;
+    translate([-cavity / 2, socket_rail_axis_y() - cavity / 2,
+               socket_flange_size[2]])
+        cube([cavity, cavity, socket_capture + eps]);
+
+    // Four base mounting holes with clear vertical driver access.
+    for (x = [-socket_mount_x, socket_mount_x], y = socket_mount_ys) {
+        translate([x, y, -socket_key_size[2] - eps])
+            cylinder(h = socket_flange_size[2] + socket_key_size[2] + 2 * eps,
+                d = screw_clearance_diameter);
+        translate([x, y, socket_flange_size[2]])
+            cylinder(h = socket_gusset_height + eps,
+                d = socket_mount_tool_diameter);
+    }
+
+    // Two screw levels through both side walls create four M5 clamp points.
+    for (h = rail_screw_heights) {
+        translate([-socket_flange_size[0] / 2, socket_rail_axis_y(),
+                   socket_flange_size[2] + h])
+            rotate([0, 90, 0])
+                cylinder(h = socket_flange_size[0], d = rail_screw_diameter);
+        translate([-collar_half_x - eps, socket_rail_axis_y(),
+                   socket_flange_size[2] + h])
+            rotate([0, 90, 0])
+                cylinder(h = rail_screw_head_depth + eps,
+                    d = rail_screw_head_diameter);
+        translate([collar_half_x - rail_screw_head_depth,
+                   socket_rail_axis_y(),
+                   socket_flange_size[2] + h])
+            rotate([0, 90, 0])
+                cylinder(h = rail_screw_head_depth + eps,
+                    d = rail_screw_head_diameter);
+
+        // Driver tunnels exist only outside the collar, preserving the side
+        // wall while allowing a socket driver through each buttress.
+        translate([-socket_gusset_outer_x - eps, socket_rail_axis_y(),
+                   socket_flange_size[2] + h])
+            rotate([0, 90, 0])
+                cylinder(h = socket_gusset_outer_x - collar_half_x + 2 * eps,
+                    d = rail_tool_diameter);
+        translate([collar_half_x - eps, socket_rail_axis_y(),
+                   socket_flange_size[2] + h])
+            rotate([0, 90, 0])
+                cylinder(h = socket_gusset_outer_x - collar_half_x + 2 * eps,
+                    d = rail_tool_diameter);
+    }
+}
+
+module socket_service() {
+    difference() {
+        socket_positive();
+        socket_cutouts();
+    }
+}
+
+module socket_print() {
+    translate([socket_flange_size[0] / 2, -socket_rear_y,
+               socket_key_size[2]]) socket_service();
+}
+
+module reference_rail() {
+    color([0.08, 0.08, 0.09, 0.8])
+        translate([plate_width / 2 - rail_size / 2,
+                   datum_y + socket_rail_axis_y() - rail_size / 2,
+                   plate_height + socket_flange_size[2]])
+            cube([rail_size, rail_size, 400]);
+}
+
+module reference_feet() {
+    foot_points = concat(
+        [[grid_xs[0], rear_foot_ys],
+         [grid_xs[len(grid_xs)-1], rear_foot_ys]],
+        [[grid_xs[0], grid_ys[len(grid_ys)-1]],
+         [grid_xs[len(grid_xs)-1], grid_ys[len(grid_ys)-1]]]
+    );
+    for (p = foot_points) {
+        color([0.05, 0.05, 0.05, 0.8]) {
+            translate([p[0], p[1], -foot_nut_height])
+                cylinder(h = foot_nut_height, d = foot_nut_diameter);
+            translate([p[0], p[1], -foot_nut_height - foot_pad_height])
+                cylinder(h = foot_pad_height, d = foot_pad_diameter);
+        }
+    }
+}
+
+// Two-piece calibration coupon, modeled directly in print orientation.
+coupon_size = [165, 110, 3.2];
+coupon_boss_height = 15;
+coupon_rail_xs = [20, 60, 100, 140];
+coupon_rail_y = 23;
+coupon_fit_center = [82.5, 90];
+coupon_fit_outer = [64, 34];
+coupon_fit_height = 6;
+coupon_key_center = [200, 90];
+coupon_key_cap = [56, 26, 2];
+coupon_key_handle = [40, 6, 8];
+
+assert(coupon_fit_height == socket_key_size[2],
+    "Coupon socket depth must match the production tongue");
+assert(len(coupon_rail_gaps) == len(coupon_rail_xs),
+    "Each rail gauge must have one layout position");
+assert(len([for (gap = coupon_rail_gaps)
+        if (gap == rail_size + 2 * rail_clearance) gap]) == 1,
+    "Production rail cavity must appear once in the coupon gauges");
+assert(coupon_rail_xs[0]
+        - (coupon_rail_gaps[len(coupon_rail_gaps) - 1]
+           + 2 * socket_side_wall) / 2 >= 0
+        && coupon_rail_xs[len(coupon_rail_xs) - 1]
+           + (coupon_rail_gaps[len(coupon_rail_gaps) - 1]
+              + 2 * socket_side_wall) / 2 <= coupon_size[0],
+    "Rail gauges exceed the main coupon width");
+assert(coupon_fit_center[0] - coupon_fit_outer[0] / 2 >= 0
+        && coupon_fit_center[0] + coupon_fit_outer[0] / 2 <= coupon_size[0]
+        && coupon_fit_center[1] - coupon_fit_outer[1] / 2 >= 0
+        && coupon_fit_center[1] + coupon_fit_outer[1] / 2 <= coupon_size[1],
+    "Coupon fit socket exceeds the main coupon outline");
+assert(coupon_key_center[0] - coupon_key_cap[0] / 2 > coupon_size[0],
+    "Coupon tongue must remain a physically separate print");
+assert(coupon_key_center[0] + coupon_key_cap[0] / 2 <= 256
+        && coupon_key_center[1] + coupon_key_cap[1] / 2 <= 256,
+    "Coupon and separate tongue exceed the X2D build area");
+
+module coupon_outline_2d() {
+    translate([coupon_size[0] / 2, coupon_size[1] / 2])
+        rounded_rect_2d([coupon_size[0], coupon_size[1]], 4);
+}
+
+module coupon_accent_2d(clearance = 0) {
+    offset(delta = clearance)
+        translate([8, 6]) square([75, grid_line_width]);
+}
+
+module coupon_positive() {
+    linear_extrude(height = coupon_size[2]) coupon_outline_2d();
+    for (i = [0 : len(coupon_insert_diameters) - 1])
+        translate([14 + i * 24, 56, coupon_size[2]])
+            cylinder(h = coupon_boss_height - coupon_size[2], d = insert_boss_diameter);
+
+    // Four production-style closed collars, left-to-right 20.0-20.3 mm.
+    for (i = [0 : len(coupon_rail_gaps) - 1]) {
+        gap = coupon_rail_gaps[i];
+        outer_x = gap + 2 * socket_side_wall;
+        outer_y = gap + 2 * socket_end_wall;
+        translate([coupon_rail_xs[i], coupon_rail_y,
+                   coupon_size[2] - eps])
+            difference() {
+                translate([-outer_x / 2, -outer_y / 2, 0])
+                    cube([outer_x, outer_y, socket_capture + eps]);
+                translate([-gap / 2, -gap / 2, -eps])
+                    cube([gap, gap, socket_capture + 3 * eps]);
+            }
+    }
+
+    // Full-depth test socket surrounding the production-size through-slot.
+    translate([coupon_fit_center[0], coupon_fit_center[1],
+               coupon_size[2] - eps])
+        rounded_prism(
+            [coupon_fit_outer[0], coupon_fit_outer[1],
+             coupon_fit_height - coupon_size[2] + eps],
+            3
+        );
+}
+
+module coupon_common_cutouts() {
+    for (i = [0 : len(coupon_insert_diameters) - 1]) {
+        x = 14 + i * 24;
+        pilot = coupon_insert_diameters[i];
+        translate([x, 56, coupon_boss_height - insert_flange_depth])
+            cylinder(h = insert_flange_depth + eps, d = insert_flange_diameter);
+        translate([x, 56, coupon_boss_height - insert_flange_depth - insert_body_length])
+            cylinder(h = insert_body_length + eps, d = pilot);
+        translate([x, 56, -eps])
+            cylinder(h = coupon_boss_height - insert_flange_depth
+                - insert_body_length + 2 * eps,
+                d = screw_clearance_diameter);
+    }
+    translate([coupon_fit_center[0], coupon_fit_center[1], -eps])
+        rounded_prism(
+            [socket_key_size[0] + 2 * socket_key_clearance,
+             socket_key_size[1] + 2 * socket_key_clearance,
+             coupon_fit_height + 2 * eps],
+            2 + socket_key_clearance
+        );
+}
+
+module coupon_key() {
+    // Separate full-size tongue. A 45-degree stop shoulder remains
+    // support-free, and the vertical rib provides a grip for removal.
+    translate([coupon_key_center[0], coupon_key_center[1], 0]) {
+        rounded_prism(socket_key_size, 2);
+        hull() {
+            translate([0, 0, socket_key_size[2] - eps])
+                rounded_prism(
+                    [socket_key_size[0], socket_key_size[1], eps], 2);
+            translate([0, 0,
+                       socket_key_size[2] + coupon_key_cap[2] - eps])
+                rounded_prism(
+                    [coupon_key_cap[0], coupon_key_cap[1], eps], 3);
+        }
+        translate([0, 0, socket_key_size[2] + coupon_key_cap[2] - eps])
+            rounded_prism(
+                [coupon_key_handle[0], coupon_key_handle[1],
+                 coupon_key_handle[2] + eps],
+                2
+            );
+    }
+}
+
+module coupon_black() {
+    difference() {
+        coupon_positive();
+        coupon_common_cutouts();
+        translate([0, 0, -eps])
+            linear_extrude(height = inlay_depth + 2 * eps)
+                coupon_accent_2d(inlay_clearance);
+    }
+}
+
+module coupon_accent() {
+    linear_extrude(height = inlay_depth) coupon_accent_2d();
+}
+
+module coupon_complete() {
+    union() {
+        difference() {
+            coupon_positive();
+            coupon_common_cutouts();
+        }
+        coupon_key();
+    }
+}
+
+module assembly() {
+    color([0.035, 0.035, 0.04]) base_black_service();
+    color([0.05, 0.25, 0.8]) accent_service();
+    color([0.035, 0.035, 0.04])
+        translate([plate_width / 2, datum_y, plate_height]) socket_service();
+    if (show_references) {
+        reference_rail();
+        reference_feet();
+    }
+}
+
+if (part == "assembly") assembly();
+else if (part == "base") print_orient_base() base_complete_service();
+else if (part == "base_black") print_orient_base() base_black_service();
+else if (part == "base_segment")
+    print_orient_base() base_segment_service(segment_index, false);
+else if (part == "base_black_segment")
+    print_orient_base() base_segment_service(segment_index, true);
+else if (part == "base_accent") print_orient_base() accent_service();
+else if (part == "socket") socket_print();
+else if (part == "coupon") coupon_complete();
+else if (part == "coupon_black") coupon_black();
+else if (part == "coupon_key") coupon_key();
+else if (part == "coupon_accent") coupon_accent();
+else assert(false, str("Unknown part: ", part));

tools/package_multimaterial_3mf.py

@@ -0,0 +1,117 @@
+#!/usr/bin/env python3
+"""Combine two aligned OpenSCAD 3MF meshes into a Bambu-friendly multipart 3MF."""
+
+from __future__ import annotations
+
+import argparse
+import copy
+import zipfile
+from pathlib import Path
+from xml.etree import ElementTree as ET
+
+
+CORE = "http://schemas.microsoft.com/3dmanufacturing/core/2015/02"
+ET.register_namespace("", CORE)
+
+CONTENT_TYPES_XML = b'''<?xml version="1.0" encoding="UTF-8"?>
+<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">
+  <Default Extension="rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/>
+  <Default Extension="model" ContentType="application/vnd.ms-package.3dmanufacturing-3dmodel+xml"/>
+</Types>
+'''
+
+RELATIONSHIPS_XML = b'''<?xml version="1.0" encoding="UTF-8"?>
+<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">
+  <Relationship Target="/3D/3dmodel.model" Id="rel0" Type="http://schemas.microsoft.com/3dmanufacturing/2013/01/3dmodel"/>
+</Relationships>
+'''
+
+
+def load_mesh(path: Path) -> ET.Element:
+    with zipfile.ZipFile(path) as archive:
+        root = ET.fromstring(archive.read("3D/3dmodel.model"))
+    mesh = root.find(f".//{{{CORE}}}mesh")
+    if mesh is None:
+        raise ValueError(f"{path} does not contain a 3MF mesh")
+    return copy.deepcopy(mesh)
+
+
+def model_xml(bases: list[Path], accents: list[Path], title: str) -> bytes:
+    root = ET.Element(f"{{{CORE}}}model", {
+        "unit": "millimeter",
+        "{http://www.w3.org/XML/1998/namespace}lang": "en-US",
+    })
+    ET.SubElement(root, f"{{{CORE}}}metadata", {"name": "Title"}).text = title
+    ET.SubElement(root, f"{{{CORE}}}metadata", {"name": "Generator"}).text = "copy-stand"
+    resources = ET.SubElement(root, f"{{{CORE}}}resources")
+    materials = ET.SubElement(resources, f"{{{CORE}}}basematerials", {"id": "1"})
+    ET.SubElement(materials, f"{{{CORE}}}base", {"name": "Black ASA", "displaycolor": "#101014"})
+    ET.SubElement(materials, f"{{{CORE}}}base", {"name": "Blue ASA inlay", "displaycolor": "#0D47CC"})
+    parts: list[tuple[int, str, Path, int]] = []
+    next_id = 2
+    for index, source in enumerate(bases):
+        parts.append((next_id, f"Black ASA segment {index + 1} - Filament 1", source, 0))
+        next_id += 1
+    for index, source in enumerate(accents):
+        parts.append((next_id, f"Blue ASA inlay {index + 1} - Filament 2", source, 1))
+        next_id += 1
+
+    for object_id, name, source, material_index in parts:
+        obj = ET.SubElement(resources, f"{{{CORE}}}object", {
+            "id": str(object_id), "name": name, "type": "model",
+            "pid": "1", "pindex": str(material_index),
+        })
+        obj.append(load_mesh(source))
+    assembly_id = next_id
+    assembly = ET.SubElement(resources, f"{{{CORE}}}object", {
+        "id": str(assembly_id), "name": title, "type": "model",
+    })
+    components = ET.SubElement(assembly, f"{{{CORE}}}components")
+    for object_id, _name, _source, _material_index in parts:
+        ET.SubElement(components, f"{{{CORE}}}component", {"objectid": str(object_id)})
+    build = ET.SubElement(root, f"{{{CORE}}}build")
+    ET.SubElement(build, f"{{{CORE}}}item", {"objectid": str(assembly_id)})
+    return ET.tostring(root, encoding="utf-8", xml_declaration=True), assembly_id, parts
+
+
+def model_settings_xml(title: str, assembly_id: int,
+                       parts: list[tuple[int, str, Path, int]]) -> bytes:
+    root = ET.Element("config")
+    obj = ET.SubElement(root, "object", {"id": str(assembly_id)})
+    ET.SubElement(obj, "metadata", {"key": "name", "value": title})
+    for part_id, name, _source, material_index in parts:
+        extruder = material_index + 1
+        part = ET.SubElement(obj, "part", {"id": str(part_id), "subtype": "normal_part"})
+        ET.SubElement(part, "metadata", {"key": "name", "value": name})
+        ET.SubElement(part, "metadata", {"key": "extruder", "value": str(extruder)})
+    ET.SubElement(root, "assemble")
+    return ET.tostring(root, encoding="utf-8", xml_declaration=True)
+
+
+def write_entry(archive: zipfile.ZipFile, name: str, data: bytes) -> None:
+    info = zipfile.ZipInfo(name)
+    info.create_system = 3
+    info.external_attr = 0o100644 << 16
+    info.compress_type = zipfile.ZIP_DEFLATED
+    archive.writestr(info, data)
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser()
+    parser.add_argument("output", type=Path)
+    parser.add_argument("--base", action="append", type=Path, required=True)
+    parser.add_argument("--accent", action="append", type=Path, default=[])
+    parser.add_argument("--title", required=True)
+    args = parser.parse_args()
+    args.output.parent.mkdir(parents=True, exist_ok=True)
+    xml, assembly_id, parts = model_xml(args.base, args.accent, args.title)
+    with zipfile.ZipFile(args.output, "w") as archive:
+        write_entry(archive, "[Content_Types].xml", CONTENT_TYPES_XML)
+        write_entry(archive, "_rels/.rels", RELATIONSHIPS_XML)
+        write_entry(archive, "3D/3dmodel.model", xml)
+        write_entry(archive, "Metadata/model_settings.config",
+                    model_settings_xml(args.title, assembly_id, parts))
+
+
+if __name__ == "__main__":
+    main()