I would also like to add that part of the value of Fusion 360 and similar packages is that they use either the Parasolid Kernel (developed by Siemens), or the A

I would also like to add that part of the value of Fusion 360 and similar packages is that they use either the Parasolid Kernel (developed by Siemens), or the ACIS Kernel (developed by Dassault Systemes), or a variant (I think AutoCAD has their own ACIS fork from long ago). If you use either of those kernels, you can handle incredibly complex geometry (or even just things that seem simple but aren't, like Fillets) with ease and good compatibility with other programs. Both of those kernels started development in the late 1980s. Parasolid alone claims over 350 3D Programs license their system. FreeCAD uses OpenCASCADE, because it's the only free option. You will notice that almost no other 3D Program, paid or free, uses it. OpenCASCADE is, compared to Parasolid or ACIS; buggy, broken, incomplete, unergonomic, and obsolete. There is almost no commercial software that uses it - they all find it better to license Parasolid or ACIS despite the heavy royalties those packages require. This puts FreeCAD in kind of a chicken-or-egg situation. The geometry kernel they use is considered unanimously inferior to the licensed kernels for almost every task, to the point that even people building new CAD programs (like the recent Plasticity beta) don't even consider it as an option. The 3D packages that license the kernels think that rebuilding ~35 years of work with extremely complex math equations requiring dozens, or even hundreds, of PhD-level math professors is too much work to justify not paying a license fee. To them, it's like saying we should rebuild Windows, but it's PhD-level math instead of APIs.