Comment by conorbergin

I think someone says this in every HN post involving CAD, but the reason FreeCAD is "buggy" and Solvespace is small and fast is Solvespace has a fraction of the power. FreeCAD uses the Open Cascade kernel, which can do complex 3d boolean and fillet operations, not having these operations severely limits the geometry you can create, and you will run into walls very quickly using Solvespace, OpenSCAD or anything else with a hand rolled geometry kernel. Even commercial projects use an off the shelf kernel, they're just difficult to write.