This is a spool center weight specifically tailored for the Eryone Two-color filament spools, the paper version. These spoools are 197mm in diameter. I found several versions of this, but I wanted something with a snug fit, and that would allow me to fill the weight with something affordable.

I used a mix of cheap heavy blanket fillers and lead pellets, but sand or any other solid material should be fine. All in all, my weight added 250g of weight to the spool, and I've tested this with an almost empty spool and it works fine in the AMS.

You will still need a border / frame for the paper spool, I used https://makerworld.com/en/models/72142#profileId-76287 .