A huge contractor in the defence and automotive industries does control an open kernel and CAD tooling: OpenCascade is owned by CapGemini. And they do build focussed CAD solutions in it (e.g. SALOME and other tools.)
Several open source CAD packages use it(FreeCAD, Cadseer, Dune3D, SALOME Shaper, KiCAD, CadQuery/Build123D, DeclaraCAD etc.)
There are firms using it for bespoke naval and aerospace applications.
The reality is CAD kernels are incredibly difficult, multi-decade projects, and part of the issue is a lot of the domain expertise in them is literally dying off or retiring.
” The reality is CAD kernels are incredibly difficult, multi-decade projects, and part of the issue is a lot of the domain expertise in them is literally dying off or retiring.”
Well, they are complex but not impossible. I understand for example zoo.dev just wrote their own.
I also understand tinkercad and womp wrote their own geometry solvers.
Not sure how to compare the above with OpenCascade (since, like you said, it’s pretty complex & public and the others are not public) but at least one can accurately say ”you can absolutely write a 3d modeler from scratch”.
Several open source CAD packages use it(FreeCAD, Cadseer, Dune3D, SALOME Shaper, KiCAD, CadQuery/Build123D, DeclaraCAD etc.)
There are firms using it for bespoke naval and aerospace applications.
The reality is CAD kernels are incredibly difficult, multi-decade projects, and part of the issue is a lot of the domain expertise in them is literally dying off or retiring.