UPDATE: Thanks to all of you who liked and supported this design I was inspired to design a new and better 608 bearing, so V2 is here! You can find it here: 608 Roller Bearing V2 

Print in place 608 roller bearing with, if I may say so, very low friction for printed part. 

O.L.S. Design - Optimal tolerances for Low friction, Stability and almost zero chance of parts sticking. Use grease lubricant for maximum result.

P.S. If you like my work please like, rate or comment. This will help me to continue materializing my ideas in this new world for me. Happy printing!
You can check my other models HERE.