This is a loader tool for the (airgun) SIG MPX/MCX RPM .177 magazine pellet belts.
The belt is a neat feed system but loading it is a fiddly process, so this tool makes it easier.
1. Lay the tool on a flat surface. 2. Lay the belt into the tool (with the metal ring part downwards) 3. Dump a small number of pellets on top of everything. 4. "Pinch" the center a bit to hold the belt steady, and shake it all around gently. (Keep it all flat on the tabletop or whatever) 5. The pellets will eventually settle tip-down into the holes. 6. Lift off the loader tool.
You will need to seat the pellets manually and clean up any excess by hand.
It's not 100% perfect but it sure helps make the process overall easier.
There is also a stackable storage tray for the belts at: https://www.thingiverse.com/thing:3001314