I based this off of Fastrack's spool centre feeder, adjusted it to fit a Rep2 better. Lowered it and also the wiringloom stays much closer to the machine with this design, so the metal clips can better hold it in place. Has nice smooth round guides with clips that allow the filament to be "clipped in" making removing/changing filament spools easy.

Printed with .27 layer height, 10% infill & 2 shells, no support or raft. Uses 2 standard size zip ties to attach to wiring harness.. Position it at the top of the wiring harness, it will fit just under the metal cutt-out for the wire harness on the Rep2, and carefully tighten the zip ties. Do not over tighten the zip ties, just tighten them enough that the guide can move with a some effort.

Clip in your filament - you may have to spread the clip apart slightly.

This thing was made with Tinkercad. Edit it online https://tinkercad.com/things/6cahhZfEpvt