vcad - Parametric CAD for AI Agents

Create 3D CAD models programmatically using the vcad MCP tools.

Available Tools

create_cad_document

Build geometry from structured primitives and operations.

export_cad

Export to STL (3D printing) or GLB (visualization).

inspect_cad

Get volume, surface area, bounding box, and triangle count.

Primitive Origins

Understanding where primitives are positioned is critical for correct placement:

Primitive	Origin	Extent
Cube	Corner at (0,0,0)	Extends to (size.x, size.y, size.z)
Cylinder	Base center at (0,0,0)	Height along +Z
Sphere	Center at (0,0,0)	Radius in all directions
Cone	Base center at (0,0,0)	Height along +Z

Positioning Operations

The at parameter accepts three formats:

1. Absolute: {x: 25, y: 15, z: 0} - exact coordinates in mm
2. Named: "center", "top-center", "bottom-center" - relative to base primitive
3. Percentage: {x: "50%", y: "50%"} - percentage of base primitive bounds

Common Patterns

Plate with Centered Hole

{
  "parts": [{
    "name": "plate",
    "primitive": {"type": "cube", "size": {"x": 50, "y": 50, "z": 5}},
    "operations": [
      {"type": "hole", "diameter": 6, "at": "center"}
    ]
  }]
}

Plate with Corner Holes

{
  "parts": [{
    "name": "mounting_plate",
    "primitive": {"type": "cube", "size": {"x": 100, "y": 60, "z": 5}},
    "operations": [
      {"type": "hole", "diameter": 4, "at": {"x": 10, "y": 10}},
      {"type": "hole", "diameter": 4, "at": {"x": 90, "y": 10}},
      {"type": "hole", "diameter": 4, "at": {"x": 10, "y": 50}},
      {"type": "hole", "diameter": 4, "at": {"x": 90, "y": 50}}
    ]
  }]
}

Cylinder with Blind Hole

{
  "parts": [{
    "name": "bushing",
    "primitive": {"type": "cylinder", "radius": 15, "height": 20},
    "operations": [
      {"type": "hole", "diameter": 10, "depth": 15, "at": "center"}
    ]
  }]
}

L-Bracket

{
  "parts": [{
    "name": "bracket",
    "primitive": {"type": "cube", "size": {"x": 40, "y": 40, "z": 5}},
    "operations": [
      {"type": "union", "primitive": {"type": "cube", "size": {"x": 5, "y": 40, "z": 30}}, "at": {"x": 0, "y": 0, "z": 5}},
      {"type": "hole", "diameter": 5, "at": {"x": 20, "y": 20}},
      {"type": "difference", "primitive": {"type": "cylinder", "radius": 2.5, "height": 40}, "at": {"x": 2.5, "y": 20, "z": 20}}
    ]
  }]
}

Linear Pattern of Holes

{
  "parts": [{
    "name": "rail",
    "primitive": {"type": "cube", "size": {"x": 200, "y": 20, "z": 10}},
    "operations": [
      {
        "type": "difference",
        "primitive": {"type": "cylinder", "radius": 3, "height": 15},
        "at": {"x": 20, "y": 10, "z": -2}
      },
      {
        "type": "linear_pattern",
        "direction": {"x": 1, "y": 0, "z": 0},
        "count": 5,
        "spacing": 40
      }
    ]
  }]
}

Circular Pattern

{
  "parts": [{
    "name": "flange",
    "primitive": {"type": "cylinder", "radius": 40, "height": 10},
    "operations": [
      {"type": "hole", "diameter": 20, "at": "center"},
      {
        "type": "difference",
        "primitive": {"type": "cylinder", "radius": 4, "height": 15},
        "at": {"x": 30, "y": 0, "z": -2}
      },
      {
        "type": "circular_pattern",
        "axis_origin": {"x": 0, "y": 0, "z": 0},
        "axis_dir": {"x": 0, "y": 0, "z": 1},
        "count": 6,
        "angle_deg": 360
      }
    ]
  }]
}

Workflow

1. Create: Use create_cad_document to build geometry
2. Inspect: Use inspect_cad to verify dimensions and volume
3. Export: Use export_cad to save as .stl or .glb

Tips

• Holes default to through-holes; specify depth for blind holes
• Use percentage positioning for parametric designs that scale
• Cube origin is at corner - add half-size to center operations
• Cylinder/cone origins are at base center - no X/Y offset needed for centered holes
• Always extend cutting cylinders past the part (the hole operation does this automatically)

Setup

Recommended: Install the vcad Claude Code plugin for zero-config setup (includes MCP server, skills, and slash commands):

claude plugin add vcad

Manual setup: Add the vcad MCP server to your Claude Code config:

{
  "mcpServers": {
    "vcad": {
      "command": "npx",
      "args": ["-y", "@vcad/mcp"]
    }
  }
}

Or run from local checkout:

{
  "mcpServers": {
    "vcad": {
      "command": "node",
      "args": ["packages/mcp/dist/index.js"]
    }
  }
}