Ender 3 Filament Roller

I couldn't find the bearings I bought for projects like this, but I had some extra 1/4 inch slingshot ammo I used in one of [Tulio's 3d printable marble mazes](https://www.thingiverse.com/thing:1385312), and I was impatient. So I created this roller for my Ender 3's filament spool holder.

I made it for my eSun PETG spools, and the fit is perfect. For wider spools like Hatchbox you can probably print 3 of the center spacers (yellow) and only one of the end spacers (blue), and the end spacer ma