Makerbot Z18 Spool Roller

This is a spool roller I designed for my clubs MakerBot Z18 printer. After realizing the bottom spool holder has many issues due to friction we started using the spool holder MakerBot recommends, https://www.thingiverse.com/thing:615307, and while this works, we very much disliked that we couldn't secure the top and have it be flush with the spool holder also there. So, after realizing old smart extruders are useful for scrap parts (specifically their bearings), this idea was born. It lets the spool glide seamlessly so there is no friction from the pull of the roll affecting prints. It also mounts from the back vents so the top cover can be secured flush in place. The mount on the back vents is a little tight on purpose so the holder isn't vibrating around loosely.