I have to cut out a 3" x 4" space for an outlet box at the bottom of a sheet of 20-gauge stainless steel. I don't have to cut out within the sheet -- merely at the bottom. I don't have the steel in hand yet but I think it would be tough to cut with the various sheet metal snips I have. Any ideas? Angle grinder with a metal cutting abrasive wheel? I have a good Makita jigsaw. Run it at a slow speed over an oiled line? Any thoughts would be welcome. (It's for a backsplash and the outlet would be just off the floor behind a range.) Thanks in advance.