Adjusted the arcs on the top to be lower so it wont touch the filament on heavily loaded spools also made the walls of the bearings slightly thicker and added a plate so you can mount on top of a Formbot Raptor or other big printer with 4040 extrusions on top.

You can use it with 2020 extrusions but the plates will overhang a bit.

You still need some way to mount the rollers on top. T nuts with thumb screws would be perfect.

My advice is to slightly heat up the plastic when inserting bearings with PLA

GREAT DESIGN BY THE AUTHOR !!!!!!