A good friend of mine dropped off a plethora of front fenders for his '65 Chevy truck. Of course, each one had either some rust or some dents. I started on the passenger side first. The fender on the left was by far the most solid of the bunch, so that is the one I fixed. It was pretty well mangled near the bottom of the door so I took a large section of the blue fender to graph into it. I specifically cut it in a region that I could get in behind it after it was all welded up. Doing this way also allowed me to fix the rust spot while the "patch" was off of the underlying structure.
The pic on the left is of the repaired rust spot on the "patch" panel. With no fender structure underneath, the back side was accessible the finish the repair with a the hammer and dolly. On the right is were I started to finish the weld of the "patch" to the original fender. I do most of the initial grinding with a die grinder and them follow up with the 2" right angle grinder.
The outside skin is done, now I have to rebuild the inner structure...