Whilst on holiday, I saw these really cool models that I thought would be an interesting challenge (just to placename drop, it was in the Japan area of Epcot).
You get four straws and cut them up at set points, then follow the instructions to get them to fit together. The build itself doesn’t use glue, just the friction between the parts. The tolerances are very precise so there were times when it didn’t seem to go as well as I would have liked, but even with my fat fingers the results are quite impressive.
The “additional” faces allows you to clip in new ones if you want to.