openscad

name	openscad
description	Generate parametric 3D models in OpenSCAD — enclosures, brackets, mounts, mechanical parts. Produce printable STL/3MF files for FDM printers (Bambu, Prusa, etc). Use this skill when the user asks to design a 3D printed part, enclosure, case, mount, bracket, jig, or fixture. Also trigger on: 'make me a box for...', 'print a case', '3D print', 'enclosure for my PCB', 'MOLLE mount', 'snap-fit', 'screw boss', 'parametric design', or any request involving physical objects that could be 3D printed. Covers OpenSCAD language, BOSL2 library, CLI rendering, slicer integration, and FDM print design rules.
metadata	{"version":"2.0","effort":"high","auto-invocable":false,"category":"hardware","compatible-claude-code":{"when_to_use":"When designing 3D printed parts, enclosures, or mechanical components","allowed-tools":["Bash","Read","Write","Edit","Glob"]}}

OpenSCAD — Parametric 3D Modeling & Print-Ready Export

Generate .scad files, render to STL/3MF, slice and print. OpenSCAD is script-based CSG — perfect for parametric enclosures, brackets, and mechanical parts where dimensions need to be tunable.

When to Use

• Enclosures for PCBs, electronics, batteries, sensors
• Mounts & brackets — MOLLE, DIN rail, wall mount, tripod, clamp
• Mechanical parts — gears, pulleys, cams, hinges, latches
• Jigs & fixtures — alignment tools, test fixtures, assembly aids
• Adapters — connector adapters, cable strain relief, antenna mounts

Quick Start

// Minimal parametric box
inner = [60, 40, 25];  // [w, d, h]
wall = 2;

difference() {
    cube([inner.x + 2*wall, inner.y + 2*wall, inner.z + wall]);
    translate([wall, wall, wall])
        cube([inner.x, inner.y, inner.z + 1]);
}

Language Reference

3D Primitives

cube([w, d, h]);                    // box (origin at corner)
cube([w, d, h], center=true);       // centered on origin
sphere(r=10);                       // sphere
sphere(d=20);                       // diameter form
cylinder(h=20, r=5);               // cylinder
cylinder(h=20, r1=10, r2=5);      // cone/frustum
cylinder(h=20, d=10);             // diameter form
polyhedron(points=[], faces=[]);   // arbitrary mesh

2D Primitives (for extrusion)

square([w, h]);
square([w, h], center=true);
circle(r=10);
circle(d=20);
polygon(points=[[0,0],[10,0],[5,10]]);
text("VARTA", size=8, font="Liberation Sans:style=Bold", halign="center");

Boolean Operations

union() { a(); b(); }          // combine shapes
difference() { a(); b(); }     // subtract b from a
intersection() { a(); b(); }   // keep only overlap

Transformations

translate([x, y, z])           // move
rotate([rx, ry, rz])           // rotate (degrees)
rotate(a=45, v=[0,0,1])        // rotate around axis
scale([sx, sy, sz])            // scale
mirror([1, 0, 0])              // mirror across plane
color("red")                   // color (preview only)
color([r, g, b, a])            // RGBA 0-1

Advanced Transforms

hull() { a(); b(); }           // convex hull (FAST — preferred for rounded boxes)
minkowski() { a(); b(); }      // Minkowski sum (SLOW — avoid for complex shapes)
offset(r=2)                    // 2D: round outward (negative = inward)
offset(delta=2, chamfer=true)  // 2D: chamfered offset

Extrusion (2D → 3D)

linear_extrude(height=10)              // straight extrude
linear_extrude(height=10, twist=90)    // twisted extrude
linear_extrude(height=10, scale=0.5)   // tapered extrude
linear_extrude(height=10, center=true) // centered vertically
rotate_extrude(angle=360)              // lathe/revolve

Control Flow

for (i = [0:4]) translate([i*10, 0, 0]) cube(5);     // range
for (p = [[0,0],[10,0],[5,10]]) translate(p) sphere(2); // list
if (wall > 2) { /* thick wall design */ }
let (d = sqrt(w*w + h*h)) echo(d);                    // local variable

Modules & Functions

module rounded_box(size, r) {           // reusable shape
    hull() for (x=[r,size.x-r], y=[r,size.y-r])
        translate([x,y,0]) cylinder(r=r, h=size.z);
}

function hyp(a, b) = sqrt(a*a + b*b);  // pure function (returns value)

Special Variables

$fn = 40;       // circle/sphere segments (global or per-shape)
$fa = 12;       // minimum angle per segment
$fs = 2;        // minimum segment length (mm)
$preview       // true in preview (F5), false in render (F6)
$children      // number of child shapes in a module

Debug Modifiers

# cube(10);    // highlight (transparent red in preview)
% cube(10);    // transparent/background
* cube(10);    // disable (comment out)
! cube(10);    // show only this

Import/Export

import("file.stl");           // import mesh
import("file.svg");           // import 2D SVG
import("file.dxf");           // import 2D DXF
surface("heightmap.png", center=true);  // heightmap → 3D

Enclosure Design Patterns

Rounded Box (hull method — fast)

module rbox(w, d, h, r) {
    hull() for (x=[r,w-r], y=[r,d-r])
        translate([x, y, 0]) cylinder(r=r, h=h);
}

Rounded Box (offset+extrude — fastest for simple shapes)

module rbox2(w, d, h, r) {
    linear_extrude(h)
        offset(r=r) square([w - 2*r, d - 2*r], center=true);
}

Shell (hollow box with open top)

module shell(outer, wall) {
    difference() {
        rbox(outer.x, outer.y, outer.z, 3);
        translate([wall, wall, wall])
            rbox(outer.x-2*wall, outer.y-2*wall, outer.z+1, max(1, 3-wall));
    }
}

Screw Boss

module screw_boss(h, od=8, id=3.2) {
    difference() {
        cylinder(d=od, h=h);
        translate([0, 0, -0.1]) cylinder(d=id, h=h+0.2);
    }
}

Snap-Fit Clip (cantilever)

module snap_clip(len=10, w=4, t=1.2, hook=0.8) {
    // Vertical beam
    cube([w, t, len]);
    // Hook at top
    translate([0, 0, len])
        cube([w, t + hook, t]);
}

Port Cutout Helper

module port_cutout(size, wall, pos) {
    // size = [w, h], wall = wall thickness, pos = [x, y] on wall face
    translate([pos.x - size.x/2, -0.1, pos.y - size.y/2])
        cube([size.x, wall + 0.2, size.y]);
}

MOLLE Slot Grid

module molle_slots(cols=2, rows=3, wall=2.5) {
    // Standard PALS: 25.4mm horizontal, 38.1mm vertical
    slot_w = 4; slot_h = 32;
    h_space = 25.4; v_space = 38.1;
    for (c=[0:cols-1], r=[0:rows-1])
        translate([c*h_space - slot_w/2, r*v_space - slot_h/2, -0.1])
            cube([slot_w, slot_h, wall+0.2]);
}

Text Emboss / Deboss

// Debossed (into surface)
difference() {
    cube([50, 20, 3]);
    translate([25, 10, 2.5])
        linear_extrude(1)
            text("VARTA", size=8, halign="center", valign="center");
}

// Embossed (raised from surface)
cube([50, 20, 3]);
translate([25, 10, 3])
    linear_extrude(0.6)
        text("VARTA", size=8, halign="center", valign="center");

Lid with Inset Lip

module lid(outer_w, outer_d, wall, lip_depth=6, tol=0.3) {
    union() {
        // Flat top
        rbox(outer_w, outer_d, wall, 3);
        // Inset lip
        translate([wall+tol, wall+tol, -lip_depth])
            rbox(outer_w-2*wall-2*tol, outer_d-2*wall-2*tol, lip_depth, 1);
    }
}

PCB Standoff

module standoff(h=5, od=5, id=2.5, base_h=1) {
    cylinder(d=od, h=base_h);           // base flange
    cylinder(d=od*0.7, h=h);            // post
    translate([0,0,h-3])
        difference() {
            cylinder(d=od*0.7, h=3);
            translate([0,0,-0.1]) cylinder(d=id, h=3.2);  // screw hole
        }
}

FDM Print Design Rules

Tolerances

Feature	Tolerance
Press-fit hole	+0.1mm over shaft diameter
Sliding fit (lid, cover)	+0.3mm per side
Screw clearance (M3)	3.2mm hole
Screw tap (M3, into plastic)	2.5mm hole
Snap-fit clearance	+0.2mm

Printability (FDM, no supports)

Rule	Value
Min wall thickness	1.2mm (3 perimeters @ 0.4mm nozzle)
Min feature size	0.8mm
Max overhang angle	45° from vertical (no supports)
Max bridge span	15mm (PLA), 10mm (PETG)
Min hole diameter (horizontal)	3mm (teardrop shape preferred)
Layer height	0.2mm standard, 0.12mm detail
First layer squish	0.04mm helps adhesion

Avoiding Support Structures

• Orient overhangs within 45° of vertical
• Use chamfers instead of fillets on bottom edges
• Teardrop holes for horizontal holes (flat at top)
• Bridge short spans (<15mm) rather than support them
• Split model into printable orientations

Material Selection

Material	Use Case	Bed Temp	Nozzle
PLA	Prototypes, indoor use	60°C	210°C
PETG	Functional parts, outdoor	80°C	235°C
ASA	UV-resistant outdoor	100°C	250°C
TPU	Flexible, shock absorbing	50°C	230°C

Common Component Dimensions

Electronics

Component	Size (mm)
Raspberry Pi 5	85 x 56.5 x 20
Raspberry Pi Zero 2W	65 x 30 x 5
Arduino Uno	68.6 x 53.4 x 15
ESP32 DevKit	51 x 28 x 7
SSD1306 OLED 0.96"	PCB 27.5 x 27.8, active 23.7 x 12.9
SSD1306 OLED 1.3"	PCB 35 x 33, active 30 x 17
18650 cell	65 x 18.5 (diameter)
USB-C port	8.94 x 3.26 (cutout: 10 x 4)
Micro-USB port	7.5 x 2.5 (cutout: 9 x 4)
SMA bulkhead	6.35mm hole, 9.5mm nut
RP-SMA bulkhead	6.35mm hole
M3 screw clearance	3.2mm hole
M3 heat-set insert	4.0mm hole, 5.5mm depth

Mounting Standards

Standard	Dimensions
MOLLE/PALS	25.4mm H-spacing, 38.1mm V-spacing, 4mm slot width
DIN rail (35mm)	35mm width, 7.5mm depth, 1mm thick
VESA 75	75 x 75mm bolt pattern, M4
VESA 100	100 x 100mm bolt pattern, M4
1/4"-20 (tripod)	6.35mm hole
GoPro mount	2-prong: 15mm wide, 3mm slot, 8mm spacing
Picatinny rail	22mm wide, 4.8mm slot, 9.5mm spacing

CLI Rendering & Export

# Render to binary STL (smallest file)
openscad -o output.stl --export-format binstl input.scad

# Render to 3MF (preserves units, modern format)
openscad -o output.3mf input.scad

# Override parameters from CLI (parametric batch)
openscad -o small.stl -D 'inner_w=50' -D 'inner_h=30' input.scad
openscad -o large.stl -D 'inner_w=100' -D 'inner_h=60' input.scad

# Render preview image (for documentation)
openscad -o preview.png --render --imgsize=1920,1080 --viewall --autocenter input.scad

# Batch: render multiple variants
for size in 50 75 100; do
    openscad -o "box_${size}.stl" -D "inner_w=${size}" input.scad
done

Performance tip: Add --enable manifold on OpenSCAD nightly builds for 5-30x faster rendering.

BOSL2 Library

BOSL2 adds high-level modules for enclosure design. Install to Documents/OpenSCAD/libraries/BOSL2/.

include <BOSL2/std.scad>

// Rounded cuboid with edge rounding
cuboid([60, 40, 25], rounding=3, edges="Z");

// Threaded screw hole
threaded_rod(d=3, l=10, pitch=0.5, internal=true);

// Snap-fit joint
snap_pin(size=3, thick=1.5);
snap_socket(size=3, thick=1.5);

// Hinged box
cuboid([60,40,25], anchor=BOTTOM) {
    attach(TOP) hinge_half(l=40, inner=true);
}

Don't assume BOSL2 is installed. Generate standalone .scad files using built-in OpenSCAD modules unless the user confirms BOSL2 is available. BOSL2 adds convenience but isn't required for any design task.

NopSCADlib

NopSCADlib provides dimensional "vitamins" (real-world parts) for visualization and fit-checking. Includes screws, nuts, PCBs, displays, stepper motors, fans, bearings, connectors, and more. Auto-generates BOMs and assembly instructions.

Useful for visualizing hardware inside enclosures but not required. Mock components with simple cubes if NopSCADlib isn't installed.

Slicer Integration

Bambu Studio

1. Export .stl (binary) or .3mf from OpenSCAD
2. Drag into Bambu Studio
3. If multiple parts on one plate: Right-click → Split to Objects
4. Parts must have a gap between them (≥1mm) for auto-split to work
5. Orient parts flat (open side up for shells, flat for panels)

PrusaSlicer / OrcaSlicer

Same workflow. All accept STL and 3MF from OpenSCAD.

Multi-Part Designs

Always export parts with physical separation (translate one part away from the other). This allows slicer auto-split. Alternatively, export each part as a separate STL from OpenSCAD by commenting out other parts.

Common Pitfalls

Z-Fighting (Coincident Faces)

Boolean difference() fails silently when the cutting shape is flush with the surface. Always extend cuts by 0.1mm beyond each surface:

// BAD — cutting face flush with outer surface
difference() {
    cube([10, 10, 5]);
    translate([2, 2, 0]) cube([6, 6, 5]);  // flush at z=0 and z=5
}

// GOOD — extend cut 0.1mm past each surface
difference() {
    cube([10, 10, 5]);
    translate([2, 2, -0.1]) cube([6, 6, 5.2]);
}

Performance

• Prefer hull() over minkowski() (10-100x faster)
• Use $fn=6 in preview, $fn=40-60 for export (or use $fn = $preview ? 12 : 48;)
• Avoid deep nesting of minkowski() operations
• Use linear_extrude(offset()) instead of minkowski(cube, cylinder) for rounded boxes

Disconnected Geometry (Slicer Split-Body)

Internal features (shelves, ledges, standoffs) that aren't physically connected to the main shell body will be detected as separate objects by slicers. Bambu Studio's "Split to Objects" will split them out, causing unexpected 3-part prints.

Prevention: Always union() internal features with the shell, or ensure they physically intersect the wall geometry (overlap by ≥0.1mm). If the feature is optional (e.g., a PCB shelf when the user will hot-glue instead), omit it entirely rather than leaving a floating body.

Detection: After export, import into slicer and check object count. If "Split to Objects" produces more parts than expected, you have disconnected geometry.

Non-Manifold Geometry

• No zero-thickness walls (use ≥0.1mm minimum)
• No self-intersecting shapes
• Ensure boolean operands overlap (no touching-only surfaces)
• OpenSCAD nightly's Manifold engine is stricter but produces cleaner meshes

File Size

• Use --export-format binstl for binary STL (5-10x smaller than ASCII)
• Reduce $fn on non-critical curves
• 3MF is compressed — smaller than ASCII STL for complex models

Design Workflow

1. Measure components — calipers or datasheets. Include tolerances.
2. Define parameters at top of file — all dimensions tunable.
3. Build bottom-up — shell first, then add posts/bosses, then cut holes.
4. Preview often (F5) — fast check during development.
5. Render (F6) and export STL when ready to print.
6. Slice — import STL into Bambu Studio / PrusaSlicer.
7. Test fit — print a thin slice first (linear_extrude(2) of the cross-section) to verify dimensions before full print.

Tips

• Parametric everything — put dimensions in variables at the top, never hardcode in geometry.
• Name your modules — module front_shell(), module back_panel(), not inline geometry.
• Separate parts for printing — offset parts on the build plate with translate().
• Test fit cuts — print just the lid or just the port area as a thin slab to verify fit.
• Comment cutouts — label what each difference() operation removes.
• Version control — .scad files are text, git-friendly. Commit them.
• Chamfer bottom edges — 0.5mm chamfer on print bed contact edges prevents elephant foot.
• Heat-set inserts — stronger than screwing into plastic. 4.0mm hole for M3 insert.

Changelog

• 2026-03-12: Created skill — language ref, enclosure patterns, FDM rules, CLI, BOSL2, slicer integration
• 2026-03-12: Added disconnected geometry pitfall (OLED shelf split-body in Bambu Studio)
• 2026-03-12: Antenna pass-through holes need 12mm for rubber duck WiFi antennas (not 6.5mm SMA)
• 2026-03-12: MOLLE slots verified: 4mm wide x 32mm tall, 25.4mm H / 38.1mm V spacing
• 2026-03-12: SSD1306 0.96" OLED exact dims: PCB 27.5x27.8mm, active 23.74x12.86mm, 4-pin 2.54mm