Push Plastic makes inexpensive MasterSpools and 500 gram filament refills for MasterSpools. When my order arrived I realized that the three slots on each side would snag on spool holders with bearings or rollers, both of which I use.

I solved the problem by designing a snap-on ring which lets the spool turn smoothly. This barely fits on the bed of my Prusa i3 MK3 printer. To successfully slice it I had to turn off the skirt (Skirt and Brim: 0 Loops in Prusa Slicer).

Print in PLA, PETG, whatever.