Filament Spool Weight

I got a Eibos Cyclopes and while I love the machine, when the spool runs low on filament I had issues with the spool sliding off the tracks. So, I designed a little weight that'll pop into (almost) any spool and add some weight to it to help keep it in place while it's being unfurled.

I used a stack of Canadian quarters as the weights for the insides. A little dab of superglue will hold the cap in place. Shouldn't need any supports.