If it's worth having, it's worth over-engineering.

This is designed to hold 7 (dead hopefully) AA batteries. The two halves screw together though the center hole / hub of your filament spool. Should add sufficient weight to nearly-empty spools to allow them to be used in the AMS without potentially getting jammed, dislocated, or otherwise made fun of for being a pathetic wimp.

50mm is the smallest diameter I could get, and it is suitable for basically any spools I've used. But if you like a better fit for spools with larger holes (including the Bambu spools), then 53's your huckleberry.

I've included two versions of each. Loose ones have battery cutouts that are not constrained…useful if your printer maybe doesn't have the greatest of tolerances when printing circles. Snug ones “grip” the batteries and limit rattle…useful if you don't have all 7 slots filled or just can't abide by a rattle in your roll. Like me.

Did I mention these were over-engineered? But seriously, why just tape together batteries and toss them into your spool when you can have a work of art like this? :D

Print using basically anything on any setting with no support. I just did 20mm in PLA with 4 walls for peace of mind. But it's overkill…just like the model itself.

Enjoy!