I'm late to the party but my children have just been bitten by the 'fidget spinner' bug!
I've been printing some great Thingiverse spinners and Ebay'ing 608 bearings but then thought, why not print the bearing as well?
So a quick model and print produced this item - and it does spin!
Just add a spinner of choice and thumb caps.
Please don't expect 'real' bearing performance but if you have your printer nicely tuned (not over-extruding) then this can be used in spinners.
This print will need supports but just the minimum under each 'ball bearing'
If you printer isn't set up correctly, especially over extruding, it will render the bearing fused together.
You will need to 'break' the ball bearings away from the cage.
Use a small pointed blade/screwdriver to get between two balls and twist to break the connection with the outer cage.
Do that all the way around the bearing and it will start to rotate.
Add fine oil/Vaseline to lube and the more you play with it the smoother it will rotate!
However, if your printer supports are too dense or your printer is over-extruding then it may be fused too much.
Aim for an under extrude setup if you have no luck with standard settings.