2 You can remove rusted metal with either an acetylene torch, plasma cutter, or air-powered cutoff wheel. Here we’re using a plasma cutter. When using a plasma cutter or torch, use extra care and caution for what’s on the other side of the metal. The heat and sparks can easily catch old gunk and oil on fire. You’ll notice that we’re cutting well inside our mark—this is intentional. In our floorpan’s case, not all the metal was bad, and when you’re restoring a car, the more factory sheetmetal you can retain the better.