Note: This should be printed in a FLEX filament. I used NinjaFlex with high (90%) infill but feel free to try others.
This is a pad for the excellent FSR Mounts by EclecticAngler. The pads help distribute the contact area of the plunger.
They have holes in the center in case your screws protrude from the plungers (like mine do) and you can't use the silicone pads provided in the kit.
Simply print three of them and pop them into your mounts.
Print in FLEX filament (e.g. NinjaFLEX) at high infill. Printing in a firm filament like PLA or ABS sorta defeats the purpose of the pad.