I buy PETG in bulk but those spools are too big to fit in my Sunlu filament dryers.  This is an adapter that allows you to combine two Prusa spools together into one super-wide spool.  It fits in my Sunlu dryers occupying two side-by-side spots.

You may also be interested in this long leadscrew for Pastamatic (https://www.printables.com/model/1632675-pastamatic-leadscrew-for-double-wide-spools) if that is how you wind your spools.

Suggestion:  After assembling, add a few drops of glue between the cardboard tubes, both sides and both ends of the coupler.  It is tight, but there is a lot of force on them once wound and that small precaution can avoid disaster.