[mark_in_manc]

Nice idea. A de-facto wad punch can also be made by using a thick steel washer and a steel ball bearing that's bigger than the hole in the washer. So long as the washer hole is sharp-edged and the ball is not much bigger than the hole, hitting the ball into the hole with a hammer, with the stuff to be cut placed between ball and washer, will cut a neat circle.

This will also sometimes cut if you force the ball in with mole grips across ball and washer - useful if you need to cut a hole in something (like a tent flysheet or a tarp) which is already in the air, with nothing to hit against.