I'm not sure what to call this. They're little pads that go on large Kobalt "Magnum Grip" adjustable pliers, and will hold "large" snaps in place. Two of the "feet" (one top, one bottom) seat the flatter side of the snap, and one of each for the "pointy" side.

The snaps are 5/8" "Heavy Duty Snap Fasteners" from Jo-Ann Fabrics, #981-1

I printed them in nylon (Taulman 910 alloy) which I highly recommend, it's a neat material for this sort of thing.

MakerGear

MakerGear M2

Doesn't Matter

Yes

0.1

I printed pretty fine but it'd be great at lower resolution like 0.2 or more. Supports are needed, and should be easy to remove.