I use almost exclusively Eryone filament (not sponsored!) and although I tried pretty much all the spool rings to adapt the cardboard spools for use within the AMS - I found that they pretty much all had one of two problems. The first is that the spools would ride up in the AMS and rock back and forth somewhat violently and the other was that they would come off the edges of the spools and get caught in the AMS. This was even more noticeable if the spool edges were not pristine and had defects or warp or damage to them.

This design may not be the fastest or lightest on filament but the model prints in around 10 minutes and uses just under 8 grams of filament which I am pretty happy about.

I finally settled on this design - it is a nice snug fit with the spool but not too tight to allows for any deformities of the cardboard - but the secret sauce are the retainer pins. The idea is that the pins fit to 2 sets of the holes on the side of the spool (leaving 2 sets free for threading the end of the filament) and are screw threaded. This ensures they stay firmly attached to the spool and also reduces slippage and bobbles when the spool is turning within the AMS.

I have uploaded three profiles with different size screw threads… My advice is to start with the M4.0 and if that is too loose use the M4.5 and if too tight use the M3.5 profile. Personally I use the M4.5 profile and this actually slightly deforms the holes and is a perfect fit - but if you are worried about damaging the cardboard then please use the M4.0 or M3.5 but be aware that this will give less grip.

Comments and suggestions are welcomed as always.