Kazmar's bearing: https://www.printables.com/model/587056-ptfe-tube-bearing-608
since the spool holders don't have much load, these PTFE bearings work great
The author remixed this model.
I added 10mm to the center of the spool holder to fit my thicker spools. I also used Kazmar's PTFE bearings and added a PTFE guide tube for above printer mounting