We used a stretching technique to change the arc of the bend in the flange. When backed up with something as hard or harder than the metal you're working with, sheetmetal will stretch when you hit it with a hammer. You can really stretch it out when you use something sharp like a chisel. The metal under the point flattens and squishes outward. Do this along the edge of a piece of steel and it will start to curve. To stretch our flange, we hammered along the inside edge (the part facing down to the ground). You can see the sections where the metal is dimpled in the photo on the right. Doing this opened up the curve of the flange and we were able to match the shape of the wheelhouse. Remember, you have to hammer against something hard or this will not work. We used the flat section of our vise as an anvil.