Another thing to be aware of, is that if you repair a damaged portion of the door, then all of the repaired area, including the weld, (if it is a welded patch), must be below the contour of the surrounding metal. This is best accomplished with a dolly and a flat faces hammer. If any of the repaired area sticks up above the surrounding surface, then you will need to apply filler to a much larger area in order to 'blend" it into the surrounding contour without an obvious "bump". In a perfect world, the repaired area should set about 1/16" to 1/8" below the surrounding metal, before any filler is applied. If you get it really close, but it is still visible after a few coats of primer have been applied, then you can try a very light coat of 2-part "blending putty", which is a very liquid form of body filler that can be lightly trowelled with a good spatula around the interface between the repaired area and the undamaged area. This stuff sets up quickly and is much easier to sand than the normal body filler. It feather edges extremely well, to 'blend" the repair into the surrounding bodywork. This stuff has a bad name in the industry, because before the advent of 2-part formulaes, it would continue to shrink for about 6 months after it was applied, and the bodywork would show up 3 months after the fact under the finished paint. Now that the stuff is available in a 2 part formulae, it cures completely due to a chemical reaction, not evaporation, so shrinkage is not as big an issue. I use a product called "Evercoat" by the makers "Rage" body fillers, and am very pleased with it.----Expert bodymen use very little of this stuff. Occasional bodymen like myself, use a lot of it. It really helps an "occasional" bodyman achieve expert looking repairs.---Brian