CAD (text-to-cad's CAD skill)

What does this skill do, and when should you use it?

The CAD skill is one of 13 skills in the earthtojake/text-to-cad repository, covering 3D modeling of mechanical parts and assemblies. It instructs the agent to write decorated Python model scripts (build123d-based) that a pinned cadgen CLI builds locally into STEP, with maintainable STL, 3MF and GLB mesh outputs. The workflow also covers project organization, resolving geometry references from prompts, measuring and validating geometry, reviewing snapshots of its own work, and opening existing STEP/STP, STL, 3MF and GLB files in a local CAD Viewer. The repository is MIT-licensed and runs everything through uv, downloading its runtime on first use.

• Reads/edits decorated build123d Python model scripts and runs python <model>.py to regenerate STEP outputs
• Exports meshes via @stl/@threemf/@glb decorators or one-off cadgen stl/3mf/glb build commands
• Resolves prompt references like /path/assembly.step#o1.2.f7 with read_scene + scene.resolve() and measures properties such as face area
• Writes Python geometry checks for dimensions, clearances and topology, and renders snapshots via cadgen step snapshot for self-review
• Shows models to the user with cad_show or a local CAD Viewer started with cadgen viewer --detach
• Diagnoses install/kernel issues with cadgen doctor and explains unexpected rebuilds with cadgen store why

How do you install this skill?

This skill ships with the text-to-cad collection (13 skills; this one lives at skills/cad/SKILL.md). uv must be installed first.

Claude Code

claude plugin marketplace add earthtojake/text-to-cad#latest
claude plugin install text-to-cad@earthtojake

Cursor

git clone --depth 1 --branch latest https://github.com/earthtojake/text-to-cad ~/.cursor/plugins/local/text-to-cad

Grok Build

grok plugin install earthtojake/text-to-cad@latest --trust
grok plugin enable text-to-cad

Gemini

gemini extensions install https://github.com/earthtojake/text-to-cad --ref latest --consent --auto-update

Other agents (Skills CLI)

npx skills add earthtojake/text-to-cad#latest

Claude Desktop has no skill-install command; only the MCP server config (cadgen mcp, pinned cadgen==0.7.20) is documented, added manually to the app config, then restart.

How do you use this skill?

Trigger it by describing a modeling task; the skill routes to task-specific reference docs. The core flow: find or create a decorated Python model script (e.g. src/bracket.py with @step(out="../STEP/bracket.step")), edit and run:

python src/bracket.py

Both python and cadgen are pinned uvx invocations (--python 3.13 --from cadgen==0.7.20). One-off mesh exports:

cadgen stl build STEP/bracket.step STL/bracket.stl
cadgen 3mf build STEP/bracket.step 3MF/bracket.3mf
cadgen glb build STEP/bracket.step GLB/bracket.glb

Geometry checks are hand-written Python (no inspect CLI; exploratory checks in tmp/, reusable ones in checks/). After creating or changing geometry you must render and personally read at least one snapshot:

cadgen step snapshot STEP/bracket.step tmp/review.png

Show results with the cad_show tool if available; otherwise run cadgen viewer --host 127.0.0.1 -- --detach (always pass --detach), read url from the JSON line, and return url?file=<URL-encoded absolute path> per file. Assemblies call child models and place results with .moved() or Location * shape; search $step-parts for named purchasable parts before making placeholders.

What are this skill's strengths and limitations?

How does this skill compare with similar options?

Side by side with related skills; every score comes from the same FSRS standard.

FAQ