I really like IceSL and think its getting too little attention: https://icesl.loria.fr/

It uses lua to be scriptable much like openscad, but it's got GPU support, so you can also describe surfaces as signed distance fields - in shader code...

It doesn't seem to be open source (yet?), but there are contributors listed [0] (it came out of inria, the french university, sylvain lefebvre being the lead dev[1])

Check out %appdata%\IceSL\icesl-models or thingiverse[2] for examples.

edit: formatting

  [0] https://icesl.loria.fr/about/
  [1] https://www.antexel.com/research
  [2] https://www.thingiverse.com/search?q=icesl