Designed this little holder to suit the larger spools of materials. I do not like mounting spools of filament on top of the printer as that can amplify print head movements into larger vibrations and It presents the filament at too sharp of an angle to the extruder and causes excessive wear. This should snap together and the bearings should push on, I had to use the heel of my foot but they went on nicely.

I print slowly as a rule. I am more interested in quality than speed. I have printed these at 40mm/s with first layer at 50% and then outer walls at 75%