double grip crank clamp thingy whatsit

[kwigly]

Whatsit tool with double clamping jaws joined to a pivot pin. I'm sure I've sen one before, but can't remember/find any reference. No markings found on the tool. It can attach to the rim of a pipe/tin (pic is on a 3-1/2" diameter tin) and further cranking will squeeze the sides together.
What is it ?

 

[marak]

Waist lasting clamp.

 

[kwigly]

Thanks Marak !
Supports the theory that "all unknown tools are leatherworker's tools"
A quick google search notes they're also known as a "Cordwainer's dog", or "Cordwainer's crab/lobster"
(I think I'll call mine a lobster)