After the initial big hammer, the rolling and so forth, it is time to take all the dents out. I use a wooden anvil for a lot of that. In the old days, I used to simply planish all those big dents out. Now, I get most of them out with a big hammer on the wooden anvil, and then put it on the wheel. The wheel is the big one you can see on the top. 6 inches by 2 inches, hardened tool steel and mirror polished. Under the workpiece is the anvil...essentially another wheel, but a rounded one....like a section of a bowling ball. The anvils come in various radii, and you use the one appropriate to the job at hand. The idea is not to make the deep compound curve, but rather, to smooth out the dents that DID make the compound curve. If it isn't quite deep enough, or if it is assymetrical, just put it back on the wooden anvil, and bash is some more. All the dents will come out with the wheel.
The operation from flat metal to what you see in the bottom pic only took me 20 minutes. (not counting the top rolled and roped edge)