One of the most frustrated Linux users/future users i’ve seen, are those who want to get out of the Windows world and are working in CAD or graphic design, but to be honest, i don’t agree with almost all of them, and this is why.
Those who say “Linux lacks good CAD software” (3D mechanical CAD in particular) are people who want free/open-source (FOSS) CAD software and the fact they make such a statement is not true when they generalise this.
On Linux you have lots of great 2D CAD software, free/open-source and the best i’ve seen so far is QCAD (the community edition is found on the repos of every distro i think) but i didn’t find a good, fully functional FOSS version of a 3D mechanical CAD software.
Finally DraftSight for Linux is out !!! Hope to find some time to make some absolute beginner tutorials i promised.
But if one can’t find free/open-source 3D mechanical CAD software it is not the end of the world for Linux users, there are always great commercial products. I will mention here VariCAD, a powerful but very affordable 3D mechanical CAD software. Also great products are Siemens NX, Pro/Engineer (thew last supported Linux version is Wildfire 3, Windows users have Wildfire 5), gCAD3d, GraphiteOne, Medusa4 and names like NX and Pro/E are well known in the 3D CAD world. Rabu Gree mentioned Briscad and Ares Commander, both working on Linux, not very expensive but looking very very powerful (This is not a complete list, tell me other names and i’ll update the post).
So to say that “Linux lacks good 3D CAD software” is bad for health, a more like “Linux lacks good free/open-source 3D CAD software” would be a more sane approach.
[EDIT] thanks to Rabu Gree comments below.