My latest project, a puzzle that is also a fully functional simple machine: https://www.printables.com/model/1646908-pulley-puzzle-no-supports

@neotoy Fascinating - my kind of my question was "what is it"... and I saw the linked page saying it's "a 12 pound test pulley that is also a fun mechanical puzzle"

I also like the:

DeWalt Bit Clip
Japanese Torii Kit Card
European robin "puzzle" - no supports