I've taught myself CAD and am getting pretty competent at it. I've been 3d printing since 2014 so I'm proficient there too. I've designed lots of functional parts to solve problems for myself, and I'm getting more into doing pieces for costume design.
What type of 3d printed stuff is actually profitable to sell? Every time I consider trying to monetize it a bit I go shopping around and think that there is no way I can design something that is a better quality or at a lower price than what is already available. Then I think about the hassle of having to manage printing and shipping and dealing with customers on top of my normal job and I think that it isn't worth it.