Simple rollers with spacers I made using freecad.

I didn't like how much noise and friction was generated by the ball bearings so I made something to fix that.

if the bearings start to snag while you are tightening you can just install a leftover washer between the spacer and bearing, the roller should move with very little resistance once it is installed.

you can print it with PLA, but be mindful of the temperature, if you expect heavy use you should print it with PETG or nylon.

the tensioning spring my rub against one roller, you can remove the spring and just tighten the screw or only install one roller.

Renkforce

Renkforce Basic 3

Doesn't Matter

Yes

0.2

50

if you print with 1.2mm wall thickness the infill doesn't matter because it will all be printed solid