It is known that warped cardboard spools may cause issues in the Anycubic ACE PRO.
And of course, I experienced this issue. So, I made my own design of a spool adapter that fits the cardboard spool.
Probably all spools don't have the same dimensions, so this one is designed for eSun cardboard spools, which has a diameter of 54 mm for the center hole, and 200 mm outer diameter (54 mm spool thickness).
If you are interested in this design for slightly different dimensions, just ask 🙂
Note: This adapter may work with other Multi Material Units, or not. I can give no guarantee.
It has been already reported that it doesn't fit the Creality CFS.