We run the 10LBS/ 3K roller of filament this cannot go on top of the printer so I made this to help it work so well I thought I would share it.

Print instructions

print 3 spacers one on either side of the pulley and one between the bearings
use 2 x 625 bearings press the two bearing into the pulley with one spacer between the bearing
1 M5 x 50 bolt
2 x M5 nuts
3 spacers
the stack should go bolt, one side piece, a spacer, bearing, spacer, bearing, spacer, the other side piece, two nuts tightened against each other
I had a typo on the bearing size I put down 626 it I corrected it to be 625