I have had cardboard spools for a while. I am on the fence. They are much easier to recycle (no matter how many 1million and 1 uses for plastic spools exist). however they creak horribly on my spool holder, and are much larger than most of the similar weight poly spools i have, so i had to create bespoke spool holders for all 3 printers i have!
They don’t seem to work very well with the AMS system from Bambu. Good news is can occasionally transplant them to a reusable (and printable too) spool.
This is what I sometimes do, transfer a bit of filament to a mini roll. There are a few decent files out there for re-spooling out there.
As environmental shakey 3d printing is, I am happy to be inconvenienced by cardboard spools, as that is one disposable things we can make not-plastic.
One interesting use for the ams system is automatic filament switching for when you want to finish a spool that has ??? Kg of filament left and you need a print to finish over night. Throw the questionable one in slot one and the new one in slot two, tell they system they are they same and it will switch over on run out.
