I am looking for an easy to use 3D modeling CAD type program. I have tried CATIA however its very involved and requires very specific inputs. At the moment I am using MS Paint to just create rough outline schematics, and I would like to step up and begin transferring some of my ideas to working 3D models. I have very rough ideas that have no specific measurements or tolerances, I am just looking to create easy visual proof of concept models that would show working parts. Any ideas?