This fidget spinner is based on shape of perpetuum mobile device. It obviously doesn't work, but it is fun to spin :)
It use 608RS bearing and 8 steel balls with diameter 8.72mm.
You can buy them here
http://amzn.to/2s2K4Az
Steel balls are pressed in to the slots which are with 0.2mm bigger than steel balls.
You can buy them here http://amzn.to/2skrVkV
Printed with PLA and 0.2mm layer thickness.
Check this video how it's assembled.
https://youtu.be/vvViLtYCqrM