Made some small magnets for a Disney Cruise for Fish Extender and Pixie dust gifts. Used the ears from a nameplate then put a couple options in TinkerCad with a hole in middle or back. I found the back hole to be easiest to superglue after issues with my Ender 3 stopping and not aligning correctly. 8mm x 2mm magnets fit great, 1mm thick didn't have enough force. I found 20mm wide is a good size but also looking to possibly make some smaller sized ones for earrings.