Used by tinsmiths because it removes a slug leaving a fairly smooth edge on the "rough" side.
Available in 1/16", 3/32",1/8", or 3/16" sizes, and priced accordingly.
This tool removes a healthy slug – we recommend using a good solid surface or base, such as particle board and a 12 oz. hammer. Set punch in place and tap lightly with a hammer first so it will flatten the tin onto the base and then strike a bit harder to punch out the slug.