Бесплатные CAD-системы
2D: https://ru.wikipedia.org/wiki/LibreCAD
3D:
http://www.collabcad.com/featuresCollabCAD.html
https://sourceforge.net/projects/brlcad/
http://solvespace.com/index.pl
http://www.salome-platform.org/downloads/current-version
+
https://www.rs-online.com/designspark/home
https://www.onshape.com/cad-features
2D: https://ru.wikipedia.org/wiki/LibreCAD
3D:
http://www.collabcad.com/featuresCollabCAD.html
https://sourceforge.net/projects/brlcad/
http://solvespace.com/index.pl
http://www.salome-platform.org/downloads/current-version
+
https://www.rs-online.com/designspark/home
https://www.onshape.com/cad-features