Hubs to hold your spool in typical 8mm spool holders with print-in-place roller bearings.
Apparently the spools are not as standard as I thought. Got a new one from 3D Mars and the hole was bigger. Use the original hubs for spools up to around 54mm and the large version for ones up to 57mm
I used 0.2 with a 0.3mm nozzle
The two hubs should be printed with the "flat" side down. You may need to use a raft if you get a lot of "Elephant Foot" on your first layer. The prints I have made usually needed to have a few of the roller bearings broken free so everything turns freely. If you have trouble with the bearing sticking together, try lowering the extruder temp and/or reducing the filament flow rate a bit.
I included a cover for the M8 nuts typically used. For these, pause the print at 6.8mm and drop the nuts in, then let it finish.
Press the hubs into the spool with the spacer between them on the threaded shaft. Snug up lightly with the knobs and place in holder.