This is universal spool roller unit & stand.
It uses 608zz bearings, no bolts and nuts are required to assemble.

Roller parts is 12cm long which should be fit for most of filament bobbin, I hope.

If you want to use roller units different ways, you can design a stand of your own to meet your requirement.

Instead of using two,only one roller-unit can be mounted on frame of 'prusa i3' style printer centering a hole of bobbin, if you design stand properly.

1. Push pin through hole of bearing and snap-in to the roller holder. You might need little force to do it. (Do not try assemble pin to holder without bearing, it might not be pulled out.)

2. Make 3 more.

3. Screw each into roller.

4. Insert roller units to stand.