Made this custom length core for the spoolholder from iRoberti found here:https://www.youmagine.com/designs/low-friction-um2-spoolholderThis version use the 608 bearings, and I have included a perfect fit spacer, though you can scale that as you please.It now fits the UM spools and the slightly thicker spools from 3Dnet that we use perfectly. Enjoy.