BOMWiki/partmode

What it solves

PartMode is a browser-based parametric CAD (Computer-Aided Design) system that allows humans and AI agents to collaborate on mechanical designs. It eliminates the need for desktop CAD installations and provides a shared, exact geometry kernel so that both users and agents operate on the same source of truth rather than parallel, opaque automation states.

How it works

Built on OpenCascade WebAssembly, replicad, and three.js, PartMode uses a canonical document model (schema-5) and an exact B-rep (Boundary Representation) kernel. It offers two authority paths for editing:

• Browser-approved local projects: Users can model anonymously in the browser; agents can be granted revocable, project-scoped access to edit the open project with human approval.
• Server-headless durable projects: Agents can be granted immutable headless grants for unattended CAD work, with results stored in account-owned documents and exported via STEP.

Who it’s for

Mechanical engineers, designers, and developers building AI-driven CAD workflows who need a local-first, open-source parametric modeling tool that supports both human and agentic interaction.

Highlights

• Parametric Modeling: Includes constrained sketches, editable feature history, patterns, and sheet-metal tools.
• Assembly Management: Supports reusable part definitions, mates, and in-context component editing.
• Exact Geometry: Uses OpenCascade for B-rep evaluation, ensuring the shaded 3D view is a representation of the exact geometry.
• Agent Integration: Provides hosted MCP (Model Context Protocol) tools for agents to perform inspections, queries, and revision-safe commits.
• Interchange: Supports STEP import/export, as well as STL, AMF, and 3MF mesh exports.
• Technical Drawings: Generates exact hidden-line views in SVG and PDF formats.