CAD is hard! I think about this a lot as I'm doing a makerspace at an elementary school and adults think it needs a 3D printer, but what are kids going to print on it?

I think for me, the prerequisites for mastering CAD were 1) the practice I got visualizing 3D shapes so I could translate them into unambiguous mechanical drawings on paper (I swear, I'm not that old but my college was behind and we were the last class to actually do mechanical drawings with a pencil), and 2) having a procedural thought process from coding so that I could sequence the CAD operations to get where I want.