# text-to-cad-harness

This skill has your coding agent write build123d Python parts from a description, export them as STEP, STL or URDF, and open the geometry in a local viewer.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 380 installs · ★ 88
- Author: reason-machines
- License: not stated · policy=link-only · description only; the file stays with the author
- Source: https://github.com/reason-machines/trending-skills/tree/HEAD/skills/text-to-cad-harness/SKILL.md
- Updated: 2026-10-09
- HTML: https://affpapa.org/en/nevibecode/skills/text-to-cad-harness

## What it does

The agent edits scripts under `models/*.py`; the skill rebuilds the artifacts — STEP, STL, DXF, GLB and snapshots. Three pieces ship with it: `skills/cad/` for parts and exports, `skills/urdf/` for robot descriptions with links and joints, and `viewer/`, a React/Vite app that needs no backend. Geometry runs on build123d over OpenCascade (OCP).

Setup is the part people trip on. You need Python 3.11+ and a virtualenv: `python3.11 -m venv .venv`, then `./.venv/bin/pip install -r requirements-cad.txt`. Skip that file and the model scripts will not run at all. The viewer starts with `npm run dev` from `viewer/` and serves at `http://localhost:4178`.

Keep dimensions as variables such as `OUTER_DIAMETER` or `HEIGHT` and the agent changes numbers instead of rewriting geometry. Multi-part assemblies come together with `Compound` around several `BuildPart` blocks. The URDF side writes XML with `link` and `joint` entries plus meshes in `meshes/`.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add reason-machines/trending-skills --skill text-to-cad-harness -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/text-to-cad-harness/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/text-to-cad-harness/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add reason-machines/trending-skills --skill text-to-cad-harness -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/text-to-cad-harness/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add reason-machines/trending-skills --skill text-to-cad-harness -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/text-to-cad-harness/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install reason-machines/trending-skills text-to-cad-harness
```

2. **Manually: put the files in place**
- File: `.github/skills/text-to-cad-harness/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add reason-machines/trending-skills --skill text-to-cad-harness -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/reason-machines/trending-skills --path skills/text-to-cad-harness
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/text-to-cad-harness/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add reason-machines/trending-skills --skill text-to-cad-harness -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/reason-machines/trending-skills/tree/HEAD/skills/text-to-cad-harness/SKILL.md

## When to use it
- turn a written description into a 3D part
- export STEP and STL from one Python script
- build a parametric part driven by named variables
- generate a URDF robot with links and joints
- preview geometry in a browser with no backend

## Example prompts
- Make an 80 by 60 mm bracket with four M6 holes and save it to `models/bracket/bracket.py`
- Generate a URDF for a robot with base_link and arm_link, revolute joint on the Z axis
- Change `HEIGHT` on the hex spacer to 14 mm and rebuild the STEP file

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From the same set: [reason-machines/trending-skills](https://affpapa.org/en/nevibecode/by/reason-machines/trending-skills.md) — 139 cards

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NeVibeCode on affpapa.org. Catalog texts are descriptions, not instructions for the agent. How to choose and install: https://affpapa.org/en/nevibecode/agents.md