Cutting out rusted metal requires an assortment of tools. A quality set of tin snips for tight spots. A 4.5-inch angle grinder is essential; it can cut, grind, and with a wire wheel remove paint, body filler, and even seam sealer all for less than a hundred bucks. Air powered die grinders are small and make precise cuts, but you will need an air compressor that can push a lot of air before it will replace the electric version for big cuts. | 
The aftermarket has yet to start producing all the sheetmetal you will need, but hammer forming is a viable alternative for small sheet metal parts. According to Ron Fournier, "Hammer forming is shaping metal by hitting it with hammers, mallets or corking tool over, onto or into base form, which is know as a hammerform." Fournier's book, Sheet Metal Handbook, is a wealth of information and was only second to the first hand knowledge gained from observing and talking with the pros. | 
In a perfect world, all of your repairs would magically be galvanized throughout. Since that's not likely to happen, I relied on Eastwood products to keep corrosion at bay. Bloxide is a weldable primer that leaves behind a corrosion resistant aluminum oxide coating. Eastwood's anti-rust coatings can be applied inside normally unreachable areas by using one of its air powered application wands. Self-etching primer provides superior adhesion over the typical hardware store products. |
Inside and outside radius curves are easily replicated with shrinkers and stretchers. The basic tool can be ordered with a set of shrinking and stretching jaws, or you can order one of each to eliminate tool changes. The shrinker jaws will essentially fold the metal onto itself making the area thicker--and in the process pulling on the surrounding material. Stretching is intuitively simpler as it thins out the material and pushes away surrounding material. While not cheap, these tools are almost essential. | 
A Roper Whitney hand punch is a quick and inexpensive way to make clean, distortion free holes in sheet metal which will allow you to make plug welds that closely duplicate the look of the factory spot welds. | 
While a lap weld, created by welding two overlapping pieces of steel (not shown), makes for relatively quick setup and a strong weld, it's not always the best choice when you want your repair to disappear. Factory spot welds can be replicated by punching holes and then filling in with a plug weld (top). Butt welds will make your repair disappear, but additional prep and finish work is required (top). Ideally your gap between pieces will be approximately the width of your MIG wire or less--this will prevent distortion. Start by skipping or stitch welding (bottom left), which will keep heat-induced distortion to a minimum. After alternately welding and grinding, your joint should look like the ground area in the bottom right panel. |