IMO, The only way to go is welding. take sheet metal, cut it, shape it, then mig weld it. Be very careful that you take your time when welding. You can easily warp the metal if you get the area to HOT because it is so thin. Grind down the welds a little, and then use filler/bondo to smooth things out. Make sure to block out the body work and try to finish your body work w/ 180grit. I would wait about a week or so after primer before painting to allow for body work shrinkage, so sand scratches and waves dont show thru the paint. Anyways -- good luck, this is the way to go if you want it to last and look good.