After printing tri spinner toys for friends and family, I became less and less satisfied with the finger plug/holders included. They were either too close (and drag on the bearing edges) or would be too loose and fall out.

This is my improved plug. It's got a ridge to keep the edges of the plug about .75mm away from the bearing surface, preventing it from dragging. It's also a very snug fit, but will allow itself to be removed/reinserted without breakage.

Enjoy!

tinkercad original here for your tinkering pleasure: https://tinkercad.com/things/ipBs6pSkkTh