Content
# OpenSCAD MCP Server
[](https://www.npmjs.com/package/openscad-mcp-server)
[](https://www.npmjs.com/package/openscad-mcp-server)
[](https://github.com/fboldo/openscad-mcp-server/actions/workflows/ci.yml)
An MCP (Model Context Protocol) server that renders **PNG previews** and **STL geometry** from OpenSCAD (SCAD) source code. It is designed to support **iterative, agent-driven CAD workflows**, where models can be previewed visually and exported for downstream use (e.g. fabrication, simulation, or inspection).
⚠️ **Beta**
This MCP server is currently in beta. Performance, APIs, and capabilities may change. Issues and contributions are welcome.
## Use cases
- **Iterative agent-driven modeling**
Agents generate or modify OpenSCAD source, render PNG previews to evaluate shape and proportions, and refine the model across multiple turns.
- **Geometry artifact generation within MCP contexts**
Agents export STL files as concrete geometry artifacts that can be passed to downstream tools, stored, inspected, or handed off to other MCP-enabled systems.
- **Visual grounding for parametric design**
PNG previews provide visual grounding for parametric or programmatic SCAD code, reducing hallucination and enabling agents to reason about spatial changes.
- **Design validation and comparison**
Agents can render multiple variants of a model (e.g. parameter sweeps) and visually compare results before deciding which geometry to persist or export.
## Available Tools
- `render_scad_png`: Renders a PNG preview image from SCAD source.
- Input: `scadCode` (string), optional `width`/`height` (numbers), optional `cameraPreset` and optional `cameraPosition`
- `cameraPreset`: one of `isometric`, `front`, `back`, `left`, `right`, `top`, `bottom`
- `cameraPosition`: `{ x, y, z }`
- Output: MCP `ImageContent`
- `export_scad_stl`: Exports an STL generated from SCAD source.
- Input: `scadCode` (string), optional `filename` (string)
- Output: MCP embedded resource (STL)
## Skill
This repository also includes an [OpenSCAD iterative modeling skill](skills/openscad-iterative-modeling/SKILL.md) that demonstrates how to use this MCP server to support an iterative SCAD → PNG → critique → refine loop.
## Limitations
- **Performance**: Rendering complex SCAD models can be slow, especially in a WASM environment.
- **Feature support**: Not all OpenSCAD features may be fully supported or may have limitations in the WASM version.
- **Fonts**: Text rendering is not currently supported. Support is planned for a future release.
## Installation
The published package is intended to run over stdio. Configure it in your MCP client using `npx`:
```json
{
"mcpServers": {
"openscad": {
"command": "npx",
"args": ["-y", "openscad-mcp-server"]
}
}
}
```
### Using the Skill
[Agents skills](https://github.com/agentskills/agentskills) are a simple, open format for giving agents new capabilities and expertise.
The most straightforward to use the OpenSCAD iterative modeling skill is to install it using the [skills CLI](https://github.com/vercel-labs/skills):
```bash
npx skills add fboldo/openscad-mcp-server --skill openscad-iterative-modeling
```
## Local development
- Install deps: `bun install`
- Stdio (matches how clients run it): `bun index.ts --stdio`
- HTTP (useful for manual testing): `bun index.ts`
- Port: `MCP_PORT` (default `3000`)
- Endpoints: `GET /health`, MCP at `POST /mcp`
- MCP Inspector: `bun run dev`
## Similar Projects
- [jhacksman/OpenSCAD-MCP-Server](https://github.com/jhacksman/OpenSCAD-MCP-Server)
This project provides a different approach relying on generating images from user prompts, followed by 3D reconstruction and even 3D printer discovery. It's a very interesting project, and I recommend checking it out if you are interested in OpenSCAD and MCP servers.
- [petrijr/openscad-mcp](https://github.com/petrijr/openscad-mcp)
Similar to this project, but it uses a Python-based server and relies on the OpenSCAD CLI for rendering.
## Relevant Links
- [OpenSCAD](https://openscad.org/)
- [OpenSCAD WASM](https://github.com/openscad/openscad-wasm)
- [Model Context Protocol (MCP)](https://modelcontextprotocol.org/)
- [Bun](https://bun.sh/)
## License
MIT — see [LICENSE](LICENSE).
