Every other ERYONE spool I have found uses ISO threads, which are difficult to print cleanly with PETG as they have a 60° overhang. This generally causes issues with internal threads as the filament may not bond to the lower layer and spider web over to another point in the arc. 

To combat this, I created this spool. It has 45° trapezoidal threads so it can easily be printed quickly at large layer heights without overhang issues.

This is a no frills spool, with holes on only one side. The core is just a bit smaller than needed, but screwing the sides together will put pressure on the cardboard core. I would also suggest snipping off the excess filament in the core so it can let go at the end of the roll without issue.

Print Profile uses Gyroid infill at 10%, but I actually used Orca slicers new 3D Honeycomb infill (not the same as Bambu 3d Honeycomb). Printed in ERYONE PETG with a 0.6 nozzle at 0.3 layer height, 2 walls, 10% infill.