OpenSCAD MCP server

OpenSCAD MCP Server

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

Agents generate or modify OpenSCAD source, render PNG previews to evaluate shape and proportions, and refine the model across multiple turns.

• Iterative agent-driven modeling

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.

• Geometry artifact generation within MCP contexts

PNG previews provide visual grounding for parametric or programmatic SCAD code, reducing hallucination and enabling agents to reason about spatial changes.

• Visual grounding for parametric design

Agents can render multiple variants of a model (e.g. parameter sweeps) and visually compare results before deciding which geometry to persist or export.

• Design validation and comparison

Available Tools

• renderscadpng: 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
• exportscadstl: 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

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Shortened. The full README is on GitHub.