Per a request, here's a Donutella (Tokidoki) fidget spinner that I came up with. Apparently, the skull version of the Tokidoki spinner was not daughter friendly, lol. This spinner uses (3) 5/16" nuts and (1) 608 skateboard bearing. This spinner is about 3-1/2" in diameter overall.
If your printer can bridge over the hole for the nut, you won't need supports.