“Universal” Spool Weight.

Universal is in quotes because I can't guarantee every spool ever made, but it'll surely fit most of them.

The weight has a body diameter of 52.5mm with a flange diameter of 70mm, and has a clamping thickness ranging from 54.5mm - 67.5mm. 

For reference California Filaments is the thinnest spool I have at 54mm and 3D Fuel is the thickest at 67.5mm, while Bambu spools are approximately 64.5mm.

I have Tinmorry spools and they have a weird cutout on the spool, so there's a special Tinmorry spacer to print if you want. This might help on other spools that have weird dimensions or shapes, but again, can't account for everything.

The hollow center can be filled with things like steel balls or pennies.

When filled with 10mm steel balls, and closed down to the thinnest clamping at 54mm, it adds around 285g of weight. Pennies is a somewhat similar weight. 

Fill it with anything you like. Maybe not things that will degrade and turn to dust, like rocks, probably definitely don't do rocks or sand.

Designed with finger recesses for easy assembly/disassembly, and custom 45° threads on the lid and body for easy printability.