Looks like it's easy enough to fabricate. For the area that's shaped, cut the profile from two blocks of 3/4 plywood. Clamp these on both sides of the sheet metal and hammer the shape out. A little dolly work to planish, and there you are. Use the opposite side (existing) for hole template.
The other way is to use a press if you have one. That involves making a male and female plug out of wood. Then you put the panel between them and put it in the press and smush the sandwich down. This works really well for forming small areas like that on the wing panel.
You can spot weld with a TIG torch, or puddle weld with gas or MIG. You can probably get away with just using panel bonding adhesive, which will be stronger than welding.