3d-print-modeling — a Claude Code skill for parametric 3D-print parts

Design FDM 3D-print parts as parametric Python (trimesh + manifold3d + shapely, or build123d), then view and screenshot them headlessly so Claude checks the geometry by eye on every change. No GUI CAD (no OpenSCAD, FreeCAD, or Fusion). The geometry engine is pip-installable, the viewer runs in a browser, and "done" means Claude actually looked at the render from six angles, not "it's watertight, ship it."

The bundled self-contained parts viewer: every STL in a project, gridded on the print bed, grouped by category, with a searchable panel and per-part dimensions. One double-click HTML file, no server.

Why

LLMs are good at writing the Python that generates a mesh and bad at noticing the bolt hole missed the shaft, the bracket is mirrored, or two parts collide. Numeric checks (is_watertight) pass while the part is visibly wrong. This skill closes that loop: it makes Claude render the part and read the image before claiming the change works, the same discipline a human modeler uses staring at the viewport.

What it does

• Parametric-first. One build.py with a PARAMETERS block is the source of truth. Edit values, rerun, never hand-edit mesh output.
• View → screenshot → iterate. serve.py + shoot.py render iso / front / side / top + two section cuts to PNG via headless Chromium. Claude looks at the part from multiple angles, and the section cuts confirm internal features (bores piercing, cavities connecting, wall thickness).
• Parts-kit fan-out. Want a whole family of parts at once? The skill fans out one subagent per part against a shared lib.py helper API, then builds them in a single pass. Measured: 19 parts, every one watertight on first build.
• Two viewers. viewer_glb.html for a single live-reloading assembly GLB (per-part toggles, explode slider, section cut, L/W/H dimension lines, Z-up). parts_viewer.py bundles a directory of STLs into the one-file HTML grid shown above.
• FDM design rules + mechanisms references loaded on demand: print orientation, self-supporting geometry, minimum feature size, PLA vs PETG, gears and worms, press-fits and clearances, bearings, snap joints.
• Engine-agnostic. Use trimesh + manifold3d for mesh surgery on downloaded STLs, or a real BREP kernel (build123d / CadQuery) for new parts with native fillets, chamfers, and threads. Both are pip install, no system CAD.

Pairs with bambu-3mf-export to turn finished STLs into a sliceable Bambu Studio .3mf project with print settings baked in.

Install

Option 1: Manual (works everywhere, all projects)

git clone https://github.com/m-esm/3d-print-modeling ~/.claude/skills/3d-print-modeling

Restart Claude Code. The skill auto-loads when you describe a modeling task, or run /3d-print-modeling.

Option 2: Plugin marketplace (supports updates)

/plugin marketplace add m-esm/3d-print-modeling
/plugin install 3d-print-modeling@3d-print-modeling

Update later with /plugin marketplace update 3d-print-modeling.

Usage

Describe the part. Claude loads the skill and runs the loop:

Make a parametric M8 bolt and a matching nut, then a wall bracket they bolt through.

This part is too flexible. Thicken the spine to 4mm and add a 45-degree gusset, then show me the section cut.

Give me a family of 42mm beam connectors: corner, tee, cross, end cap.

Or invoke it explicitly with /3d-print-modeling.

Requirements

• Python 3.9+ for the trimesh path (Python 3.10+ for the build123d BREP path).
• Install the pinned toolchain:

  pip3 install --user -r scripts/requirements.txt
  python3 -m playwright install chromium
  

What's in here

SKILL.md                 the skill itself (workflow + FDM rules Claude reads)
references/
  fdm-design-rules.md    print orientation, supports, min feature size, PLA vs PETG
  mechanisms-and-fits.md gears/worms, keyed bores, press-fits, bearings, clutches
scripts/                 generic, copy into a project as needed
  serve.py               localhost static server for the viewer
  shoot.py               headless multi-angle Playwright renders
  viewer_glb.html        Three.js assembly viewer (toggles, explode, section, dims)
  viewer_stl.html        single-STL viewer for mesh surgery
  parts_viewer.py        bundle a dir of STLs into one self-contained HTML grid
  stlpaths.py            subsystem output router (keeps the repo root clean)
  Makefile               make build / export / viewer / shot / install / all
  requirements.txt       pinned toolchain

Security

Skills can run code. This one ships Python that Claude executes: mesh generation, a localhost static server, and headless Chromium screenshots. No network calls beyond pip / playwright install, no credential access. Read SKILL.md and scripts/ before installing, same as any skill.

License

MIT. See LICENSE.

Keywords: Claude Code skill · Claude agent skill · Anthropic · 3D printing · FDM · parametric CAD · trimesh · manifold3d · build123d · CadQuery · STL · 3MF · GLB · mesh · watertight CSG · print bed · gears · brackets · headless rendering.