filament spool holder v2

this holder the filament spool in a centered position. and rolls smoothly as you print.
the threaded tube snaps onto the ender 3 v2 spool holder. the filament spool is slid onto the threaded tube, then the screw nut is screwed onto the threaded tube to keep filament spool from sliding off.

screw on end grippers will accommodate spools with bigger holes.

i modified the front of the threaded tube to keep it from turning.