While we're on the topic of Instructables projects, here's a less known one that I made where I experimented with 3D design to recreate the famed BMW Roundel.
Definitely a lot of fun. It ended up being a holiday gift for a BMW-obsessed friend.
Harmless and interesting. (Well, maybe not entirely harmless... I did manage to steal BMW's branded Helvetica font to make the letters...). Let me know if you make a build!