This spool holder assembly allows the filament spool to rotate easily and consistently about the spools centeral axis while allowing drag adjustement to prevent unspooling and filament tangles.  It works will with filament guides shown at https://www.printables.com/model/473934-even-better-prussa-mk3s-filament-guide .

Print Instructions

Attach Joint and Inner Spindle - 3 mm layer ht, 4 perimeters and 40% infill.  All other parts use 2 perimeters and 20% infill.