If you have some patience, the finished fender will look factory pressed after you grind the welds (Photo 23). I always do the rough grinding with a heavy disc, taking the weld area almost flush with the metal, then I switch to a cut off disk for the fine work. Once the fine work is done (this includes re-welding pits and holes), I use a sander disk to clean it right up.
Welding the small missed areas and pin holes usually takes two or three tries to get right, so have patience and you will be able to make a perfect fender. Your grinder is your best friend when doing this kind of work.