OpenSCAD

The Programmers Solid 3D CAD Modeller

OpenSCAD Chat: #openscad (on IRC network libera.chat)
New Book (in Spanish): Un reloj de Sol digital
Get the source and free PDFs from github
New Book (coming soon): Make: Calculus
Build models to learn, visualize and explore
Google Summer of Code Project:
3D Viewport Graphical Enhancements
OpenSCAD Chat: #openscad (on IRC network libera.chat)

OpenSCAD is software for creating solid 3D CAD objects.

It is free software and available for Linux/UNIX, MS Windows and Mac OS X.