When I was in high school, I had a major that taught us how to design parts. I didn't choose that specialty, but some friends did. It was really interesting, and he had access to a 3D printer. We had a lot of fun with it.

Right now, I'm following a guy on YouTube who's really interesting. I think you might like it, although it's in French.

It's mostly electronics, but every time there's a 3D printer part: