I've never tried BRL-CAD but it looks really big and complex. The only other one I'm aware of is Solvespace: https://solvespace.com/index.pl https://solvespace.

I've never tried BRL-CAD but it looks really big and complex. The only other one I'm aware of is Solvespace: https://solvespace.com/index.pl https://solvespace.com/index.pl It uses it's own B-Rep for NURBS and can export STEP files. The basics are there for extrudes, revolves and helixes. Booleans are still a bit buggy, but we occasionally fix a bug or two. It's definitely the smallest NURBS kernel around at about 8000 LoC and the full program comming in at ~5MB. There is no real API for geometry though, just the constraint solver. BTW the constraint solver has also been used in one of the FreeCAD assembly workbenches, and also in this sketcher add-on for blender: https://blenderartists.org/t/geometry-sketcher-constraint-solver/1328479 https://blenderartists.org/t/geometry-sketcher-constraint-so...