[abe_m]

We have OpenCASCADE, GCAL and Solvespace. The later two are missing quite a few features relative to OpenCASCADE. Then there is Parasolid, ACIS, and whatever they call the kernel in CATIA. There are a few around. But perhaps there aren't that many ideas for innovative features for people who are interested in the area to create something new.

[ruevs]

The other "decent" commercial one that can be licensed is C3D (ASCON/АСКОН uses a CAD kernel based on it in КОМПАС 3D) but it is Russian and thus currently "behind sanctions".

Here is a bit on it from the author of Plasticity: https://www.youtube.com/watch?v=WvwiH1DOK1M it initially was based on C3D.