I bought a used Logitech G5 for 5€ unfortunately it was missing the weight cartridge.
This is a compatible cartridge which uses M6 and M4 nuts as weights.
One M6 nut is about 2,1g
One M4 nut is about 0,7g
You can Load a total of 9 M6 and M4 nuts each. You can load a total of 25g in weights. The original logitech weights give you a max of 27g, so its pretty close.
The fully loaded cartridge comes in at about 34g.
If your cooling is top notch you might get away without support, unfortionately I did not.
I used a file to make the sides smooth.
Press in nuts
Use a hammer and an appropriate screw to gently hammer the nuts in place, its supposed to be a snug fit, so nothing rattles around.
After hammering you might need to resand, mine did bulge a tiny bit.
Autodesk Fusion 360 was used to make this