The next step is to tape off the perimeter of the area to be removed. It is easier to see this when the sparks are flying. Start by cutting on the flat parts of the tailgate. Cut in the middle of the lines first until the cutter breaks through. Then, continue with the edge of the cutting wheel into the 90-degree corners. When you come to the bend in the tailgate end, cut through it about 1/8-inch deep.