I needed some strong magnetic hooks for a hanging garden I'm working on and I've been meaning to try out TinkerCAD - I am pleasantly surprised, simple yet capable environment and the learning curve is basically null. I am mostly used to working in Solidworks but I'm trying to make the move to various open source or free CAD platforms.. So far, TinkerCAD's environment has been the easiest to get started making easily 3D printable models. I'll be working on a support-free thread feature once I've got some spare time to learn more about the API.
designed to fit these magnets, this object should print easily on any machine. I'm actually really pleased with how nicely the prints turned out - TinkerCAD's STL file generator is great, I had no idea!