Question: How can you curve a piece of metal?
Option 0: Firmly hold the sheet metal in the mechanical sheet pounder.  Press on the foot pedal while you hit the sheet with a hammer to create the curve that you want and to smooth it out once the basic shape has been created.
Option 1: Firmly hold the sheet metal in the mechanical sheet pounder.  Press on the foot pedal while you move the sheet back and forth to create the curve that you want and to smooth it out once the basic shape has been created.
Answer: 1