So the is the business end of the tool that gets me into so much trouble. It is a pneumatic flanging tool.
Pic 1) This is the opening end. You insert a piece of 18 or 20 gauge sheet metal and pull the lever and both jaws come closed. The bottom side makes a flange with a step of about the thickness of 18 gauge sheet metal, about 1" wide, and the step is about 3/8" wide. The top side is a hole punch. It will punch a 3/16" hole in 18 gauge sheet metal. My flanging tool is 30 years old, sometimes you need to pull the lever a couple times at the same spot to punch the hole in 18, but it will still punch 20 with one pull.
Pic 2 The flange end at work.
Pic 3, The punch end at work.
Pic 4, A piece of 18 gauge with the flange bent, and a hole punched in the flange. If you are plug welding in floor pans, the hole is a great diameter to plug weld through. That hole is centered in the jaw width, and at max depth, the hole punches about 3/16" from the jaw.