Inspired by my desktop spool roller (https://www.thingiverse.com/thing:2172340), this roller is designed to firmly snap into place on 2020 Extrusion without any fasteners. Simply space the mounts at the desired mounting point on your rail, place your spool on the rollers, and thread the filament through one of the eyes at the base and you're ready to print. The position of the filament eyes ensure that a downward force is always applied to the spool, keeping it securely in place on the rollers (4x 608 bearings required) I hope everyone who uses this finds it helpful and as always feedback is welcome. Thanks for checking this out!
I printed this using PETG. Any of the stronger materials should work well, PLA may not be strong enough but with high infill (>75%) it may, YMMV. There is a lot of clamping force in this design and although I have not weight tested it I am fairly confident that this will support any spool weight that won't tip your printer over in the process.