I threw out my last replaceable eSUN spool a few weeks ago, then I found out they sold refills.

Could I have bought a replacement? Yes, but I'm not some $6-spending-chump. I'd rather spend 20 hours of my life and half a kilo of filament developing something that already exists and make it less-good.

These can be printed as is, and only requires 1 model that's just rotated. They use 2x M6x53mm Socket Headed Cap Screw, and 2x nuts. Material and coating are irrelevant, but points will be awarded for style.

I printed this in silver eSUN PLA+ at 0.3mm layer height with a 0.4mm nozzle in a Voron 2.4 350mm.

Features include pretty hexagons, spool locks, radiused rims to ride bearings on a spool holder, and many pockets for weight savings.