cad

The saved excerpt is a snapshot from when this skill was listed. The external source remains the complete and most current version.

---
name: cad
description: Create/edit parametric CAD models, organize CAD projects, export STEP/STL/3MF/GLB files, resolve prompt references, and measure geometry with cadgen. Open and visually review existing STEP/STP, STL, 3MF and GLB files in CAD Viewer.
license: MIT
---

# CAD modeling and inspection

Provenance: maintained in [earthtojake/text-to-cad](https://github.com/earthtojake/text-to-cad).
Use the installed local skill files for the current interface.

## Start with the task

Read only the references needed for the request.

| Task | First action | Reference |
| --- | --- | --- |
| **Create or edit a part or assembly** | Find the existing Python model, or create a decorated model below; edit source and run `python <model>.py`. | [Model contract](references/step-generation.md), [shape construction](references/build123d-modeling.md); [positioning](references/positioning.md) for assemblies |
| **Organize a CAD project** | Follow its existing layout; for a new multi-model project use `src/`, format output folders, and a model catalog. | [Project layout](references/project-layout.md), [minimal starters](references/project-template.md) |
| **Export STL, 3MF or GLB** | Add a mesh decorator for a maintained output, or run the format's `build INPUT.step OUT` command for a one-off export. | [Mesh exports](references/supported-exports.md) |
| **Resolve a reference from a prompt** | Identify its saved STEP/STP document, open it with `read_scene`, and call `scene.resolve(ref)` as shown below. | [Reference syntax and inspection](references/inspection-and-validation.md#reference-syntax) |
| **Measure or check geometry** | Write a Python check using native build123d geometry and, where useful, `cadgen.geometry`. | [Inspection and validation](references/inspection-and-validation.md) |
| **Model from an image or drawing** | Extract the specified dimensions and record meaningful assumptions. | [Interpreting the request](references/cad-brief.md) |
| **Open an existing STEP/STP, STL, 3MF or GLB** | Show it to the user. | [Show the model](#show-the-model) |
| **Review appearance or motion** | Snapshot the saved document; use declared kinematics or animation for poses and clips. | [Snapshots](references/snapshot-review.md), [kinematics](references/kinematics.md) |
| **Diagnose a failure** | Read the error and check the relevant model, geometry or command contract. | [Repair loop](references/repair-loop.md), [version migration](references/migrations.md) |
| **A message says to migrate** | Do the migration now; an unmigrated model silently loses kinematics, materials and animation. | [Version migration](references/migrations.md) |

For 2D DXF drawings use `$dxf`; this skill owns any 3D part the drawing projects.
Use the corresponding robot-description skill for URDF, SRDF or SDF.

## Setup and paths

Run cadgen through [uv](https://docs.astral.sh/uv/), so this skill's commands share
one installation, and its warm build daemon, with the CAD app's server:

- `cadgen` below means `uvx --no-config --managed-python --python 3.13 --from cadgen==0.7.17 cadgen`
- `python` below means `uvx --no-config --managed-python --python 3.13 --from cadgen==0.7.17 python`

The first run downloads that installation and the first snapshot its headless
browser; later runs reuse both.

`cadgen doctor <skill-dir>` reports the installation in use and checks that it is
the one this skill pins, and that the CAD kernel loads; use it for installation or
kernel load errors. Use the relevant
subcommand's `--help` for additional flags.

Run project commands from the CAD project root. CLI input/output paths and
`read_scene`/`read_step` paths are working-directory-relative; decorator `out=`
paths are **relative to the model script**. Anchor file inputs on `__file__`
when the model must run from any directory.

## Create or edit a model

A model is a plain Python script with a parameterless decorated function
returning a build123d shape. Use one model per entrypoint, with th