To ellaborate, when you're using cad you have to give thought to how the part will be produced as well. There are a lot of shapes that 3d can't build, there are

To ellaborate, when you're using cad you have to give thought to how the part will be produced as well. There are a lot of shapes that 3d can't build, there are minimum angles, all sorts of restrictions. And there's the nitty gritty of actually fitting real shapes together in the real world, having the right flange sizes for holding screws, nuts, etc. And then you get into wear, balance, etc.