solid123d

A bridge that runs SolidPython (OpenSCAD-style) code on the build123d BRep kernel. Change one import and existing code produces native build123d shapes instead of OpenSCAD source.

# before
from solid import translate, cube, scad_render_to_file

# after
from solid123d import translate, cube, scad_render_to_file

c = translate([10, 0, 0])(cube(10, center=True))
scad_render_to_file(c, filename="c.scad")  # writes c.step (real BRep geometry)

Every object returned is a plain build123d Shape, so bridged code mixes freely with native build123d — the intended migration path:

from build123d import fillet
from solid123d import cube

part = cube(20, center=True)
part = fillet(part.edges(), radius=2)  # native build123d from here on

Supported

• Primitives: cube, sphere, cylinder (incl. r1/r2 cones, d/d1/d2), square, circle, polygon (incl. paths holes), text
• Font resolution: text(font=...) matches fonts by family name the way fontconfig/OpenSCAD does (incl. "Family:style=Style" syntax), by scanning system font directories with fontTools and handing build123d the resolved file path. This fixes fonts with nonstandard subfamilies (e.g. "Academy Engraved LET", whose subfamily "Plain" makes OCCT's own lookup fall back to Arial).
• Transforms (callable style, translate(v)(obj, ...)): translate, rotate (vector, scalar, and axis-angle forms with OpenSCAD ordering), scale, mirror, resize, color, offset
• Booleans: union(), difference(), intersection() — plus native operators a + b, a - b, a & b
• minkowski() with a ball — minkowski()(A, sphere(r)) / minkowski()(A, circle(r)), by far the most common use of minkowski() (rounding a shape), is computed exactly as offset(A, r) — including a ball tessellated as an explicit polyhedron(), the way BOSL2 builds its rounding kernels. Exact BRep geometry, not an approximation.
• hull(), for every case with a closed-form answer — all computed as exact BRep geometry: equal-radius spheres in any arrangement (including the collinear capsule/slot idiom), equal-radius parallel cylinders sharing a span (the "rounded box from corner posts" idiom), exactly two spheres of any radii (two spherical caps sewn to their external tangent cone; overlap and containment handled), exactly two 2D circles (the keyhole/slot idiom), and any collection of purely flat-faced children (cubes, polyhedron()s, extruded polygons — the hull is exactly the convex hull of their vertices). See Known differences for what still raises.
• polyhedron(points, faces) — explicit point/face solids, with OpenSCAD's tolerance for either winding direction.
• color() that survives into STEP export — colored parts that don't share volume (disjoint, or touching, like a part sitting in a cavity cut for it) stay separate bodies, each keeping its own color, and every part is labeled with the color name you wrote (color("SteelBlue") → steelblue, numeric colors get the CSS name or hex), so multi-material models open in slicers and CAD viewers with real per-part colors and recognizable names instead of one gray COMPOUND. Genuinely overlapping colored parts fuse (their merged region has no well-defined color) and carry the first part's color. Uncolored models are entirely unaffected.
• 2D → 3D: linear_extrude (incl. center, scale; no twist), rotate_extrude (incl. partial angle)
• Export: scad_render_to_file writes .step/.stl; a .scad filename is rewritten to .step with a warning
• solid123d.utils: up, down, left, right, forward, back
• Typing aliases: OpenSCADObject and OpenSCADObjectPlus are aliases of build123d.Shape, so existing annotations like def some_obj() -> OpenSCADObject: remain correct

Known differences

• a * b intersection is not overloaded; use a & b or intersection()(a, b).
• hull() raises NotImplementedError outside the closed-form cases above — notably three or more spheres of unequal radii (their hull needs planes tangent to three spheres at once, a genuinely harder object) and mixtures of curved children. Model those explicitly (loft/sweep), or import through scad123d, which renders unsupported hulls as meshes via OpenSCAD.
• minkowski() raises NotImplementedError except for the ball cases above; general Minkowski sums have no BRep equivalent. Use offset() or fillet/chamfer on the build123d object instead.
• linear_extrude(twist=...) raises NotImplementedError.
• $fn/segments arguments are accepted and ignored — BRep curves are exact.
• scad_render() (source string) raises NotImplementedError.
• OpenSCAD modifiers (#, %, !) and import()/surface()/projection() are not implemented.

Development

just test    # or: uv run pytest