https://www.youtube.com/watch?v=kTwpA2yJ81o
https://www.youtube.com/watch?v=fN9b3ByRh7A
https://www.youtube.com/watch?v=f7qkHxG1v1E
https://www.youtube.com/watch?v=lbrKJMVWQBk
https://hackaday.io/project/12043-convert-a-polygon-mesh-to-a-solid-body-for-free
https://www.youtube.com/watch?v=avVNfIswkMU
https://wiki.freecadweb.org/Mesh_to_Part
https://www.xsim.info/articles/FreeCAD/en-US/HowTo/Create-a-solid-from-surface-meshes.html