Customizable version of the 608 Bearing Roller I submitted here: https://www.thingiverse.com/thing:3389847
By default, it's able to fit a 608 bearing, but it can be modified to fit any bearing based on the diameter and width of the new bearing.
Let me know if you need any clarification on the variables.
You'll need to generate an STL for the Male and Female sides of the roller. You can chance the sides by selecting the right value for the "BearingSide" variable.