A cool twist puzzle I found online and then modeled. Usually takes people a few minutes to figure out how to get it together.
Print two copies of the model, and then they'll twist together. Very low tolerances, so you might have to remix if your printer isn't especially precise.
Video on how to solve: https://www.youtube.com/watch?v=BKkbVMp6ssY
Amazon Basics PLA
You may have to trim up the edge that prints on the supports with some clippers or sandpaper after.