[Woberto]

Sounds like you might want to use something like finite element software, which is essentially what other programs do. FEniCS is an example of an open source library that could maybe help. People usually use something like ls-dyna or Abaqus

[namibj]

Yes, of course. But I'm specifically interested in the design side, because the analysis side is already handled by open and/or free software, due to it being so close to what a small university research group might just publish or adapt for unconventional FEM analysis.

Design software is much less easy to find, though.

[Woberto]

Ah, sorry. Have you tried rhino 3d? There are some nice additions to it like grasshopper