bosl2 — a pure-Python PythonSCAD port of BOSL2

bosl2 is a pure-Python / numpy port of the pieces of BOSL2 that this toolkit uses, with no osuse()/BOSL2 runtime dependency. Every operation hangs off an object — Path for 2-D outlines, Region for outlines-with-holes, Bezier / BezierPatch for bezier curves and surfaces, VNF for vertex-face meshes, and the Bosl2Solid primitives — so new code reads as fluent chains:

Path([[0, 0], [80, 0], [80, 60], [0, 60]]).offset(r=-2).round_corners(radius=1).polygon()

⚙️ Visual parts catalog & spec sheets →  —  the gears, hinges, joiners, cube-truss and ball-bearing modules with technical schematics and metrics measured from real rendered STL.

Rendered examples

Every documented function with a rendered example shows both the exact PythonSCAD code and what the real PythonSCAD binary builds for it, via the pythonscad-example directive (in docs/_ext/bosl2_example.py): an interactive 3-D viewer for the exported STL mesh (rotate, pan and zoom — served by the stl_viewer extension’s three.js viewer, a working drop-in for the sphinxstl .. stl:: directive), plus a download link to the mesh. Two-dimensional or open-surface examples that have no solid mesh fall back to a static preview image.

Note

The interactive viewers fetch each .stl over HTTP, so view the built docs through a web server (for example python3 -m http.server from bosl2/wiki) rather than opening the HTML files directly with a file:// URL, where browsers block the local mesh fetch. You can also embed a viewer for any STL yourself with .. stl:: path/to/mesh.stl.

A cuboid primitive:

s3.cuboid([40, 30, 20], rounding=4).show()

⬇ Download STL mesh

A bezier surface patch, meshed to a VNF and rendered as a polyhedron:

patch = [
    [[-50, -50, 0], [-16, -50, 20], [16, -50, -20], [50, -50, 0]],
    [[-50, -16, 20], [-16, -16, 20], [16, -16, -20], [50, -16, 20]],
    [[-50, 16, 20], [-16, 16, -20], [16, 16, 20], [50, 16, 20]],
    [[-50, 50, 0], [-16, 50, -20], [16, 50, 20], [50, 50, 0]],
]
BezierPatch(patch).sheet([0, -6], splinesteps=16).polyhedron().show()

⬇ Download STL mesh

Sweeping a profile along a bezier curve:

circle = [[2 * math.cos(t), 2 * math.sin(t)] for t in np.linspace(0, 2 * math.pi, 24, endpoint=False)]
Bezier([[0, 0, 5], [0, 0, 20], [25, 12, 15], [30, 4, 6]]).sweep(circle, splinesteps=24).polyhedron().show()

⬇ Download STL mesh

API reference

The modules are grouped by role, mirroring BOSL2’s own organisation. Foundational holds the primitives and transforms most models start from; Paths, regions & surfaces the advanced 2-D/3-D modelling toolkit; Math & geometry the numeric helpers; and Parts library the ready-made mechanical parts — each with a visual spec sheet in the catalog linked above.

Solid backends

Foundational

Paths, regions & surfaces

Math & geometry

Parts library

Extras