Spool Holder Modification
That looks really we designed. Anything that keeps the filament flowing smoothly from the spool to the extruder is good.
Nice job - I had done something similar for my pegboard based spools. But I discovered that the bearings actually made my spools spin too easily and led to excess filament being run off if the carriage moved quickly and tugged the filament. So I actually went back to non bearing holders. Just an observation you may want to consider adding some adjustable drag to the spool if those bearings are really smooth.
If I can figure out how to do that....... 🙄