How to Export FreeCAD Models to OpenSCAD Code

Exporting 3D designs from FreeCAD into OpenSCAD code allows you to convert visual, boundary-representation (B-Rep) models into programmatic, script-based geometry. This guide outlines the direct process for exporting parts into .scad and .csg formats using FreeCAD’s native tools, explains how geometry translates into code, and details best practices to ensure your generated scripts remain clean and editable.

1. Prepare Your Model in FreeCAD

OpenSCAD is a Constructive Solid Geometry (CSG) modeling engine. It constructs shapes using primitive solids (cubes, cylinders, spheres) combined through boolean operations (union, difference, intersection).

  • CSG-Friendly Modeling: If you want recognizable OpenSCAD code (such as cube() and translate()), build your model using basic shapes and boolean operations in the Part Workbench.
  • Complex Geometry: Models created with the Part Design Workbench (using sketches, pads, lofts, or complex fillets) can still be exported, but FreeCAD will convert complex faces into raw polyhedron() data rather than compact parametric code.

Ensure your entire model is fused into a single compound or selected as a single active body before exporting.

FreeCAD includes a dedicated OpenSCAD workbench that improves compatibility.

  1. Go to Edit > Preferences.
  2. Select OpenSCAD from the sidebar.
  3. Under the OpenSCAD executable field, browse and link the path to your installed openscad.exe (Windows) or OpenSCAD binary (macOS/Linux).
  4. This integration allows FreeCAD to process CSG trees more accurately when converting shapes.

3. Direct Export to OpenSCAD Format

The fastest way to convert your model into code is using FreeCAD’s standard export menu:

  1. In the Tree View, click on the final solid object or body you wish to export.
  2. Navigate to File > Export.
  3. In the file dialogue, click the Files of type dropdown.
  4. Select either:
    • **OpenSCAD (*.scad)**: Creates a script containing native OpenSCAD code.
    • **CSG format (*.csg)**: Creates OpenSCAD’s internal representation of the CSG tree.
  5. Choose your destination folder, enter a file name, and click Save.

4. Understanding the Exported Output

Open the newly created .scad file in OpenSCAD or any text editor to review the generated code:

  • Parametric/CSG Output: If your model was built with standard primitives and booleans, FreeCAD writes modules using standard commands:

    difference() {
    cube(size = [10, 20, 30], center = false);
    translate([5, 10, 15]) cylinder(h = 20, r = 2);
}

  • Mesh/Polyhedron Output: If your model contains complex curves, chamfers, or sketch-based sweeps, FreeCAD approximates the surfaces using a triangular mesh via the polyhedron() module:

    polyhedron(
    points = [[0,0,0], [10,0,0], ...],
    faces = [[0,1,2], [2,3,0], ...]
);

5. Tips for Clean Code Generation

  • Avoid Fillets and Chamfers Early: Adding edge fillets in FreeCAD forces the exporter to generate large coordinate arrays via polyhedron(). If parametric script readability is your goal, apply rounding in OpenSCAD using the minkowski() function instead.
  • Keep Part Hierarchies Shallow: Deeply nested Part Design features can create bloated transformation blocks. Simplify your operations in FreeCAD before initiating the export.