This is a simple fidget toy vaguely resembling a coin. It features three interlocking cut spheres that can freely rotate and will never fall out.

You can print this model as one piece. Once you removed it from your build plate, it should mostly rotate freely. In the beginning It will occasionally get stuck on rough corners and seams, but if you play with it for a couple of minutes this will stop.

I printed the model in PLA @ 0.2mm with variable layerheight on my Anycubic i3 Mega.