OpenSCAD MCP Server

npm downloads

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 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:

{
  "mcpServers": {
    "openscad": {
      "command": "npx",
      "args": ["-y", "openscad-mcp-server"]
    }
  }
}

To run it over HTTP instead (e.g. in Docker), pass --http:

MCP_PORT=3000 npx -y openscad-mcp-server --http

The server exposes GET /health and a stateless streamable HTTP MCP endpoint at POST /mcp.

Using the Skill

Agents skills 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:

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 (or --http)
  • Port: MCP_PORT (default 3000)
  • Endpoints: GET /health, MCP at POST /mcp
• MCP Inspector: bun run dev

Similar Projects

• 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 Similar to this project, but it uses a Python-based server and relies on the OpenSCAD CLI for rendering.

Relevant Links

• OpenSCAD
• OpenSCAD WASM
• Model Context Protocol (MCP)
• Bun

License

MIT — see LICENSE.