Filament spool bushing for the Prusa Mk4, for relieving friction with cardboard spools. By moving the center of rotation to the center of the spool, there is less force needed to rotate the spool. 

The spool is retained by a rubber band for easy removal with the flange side of the bushing facing the center of the spool holder.

The Prusa filament guide will need to be oriented so that it lays flat instead of at an upward angle.

The outer diameter of the bushing is 53.5mm, designed off of Overture and Duramic brand carboard spools.

If other diameters are desired, please comment and I will update and post the variants.

Happy printing!