For doing the wheel well, I started with a piece of 1" flat bar, bent in the shape I wanted:
Made a cardboard template:
Traced onto steel:
For cutting it out, I clamp a straight edge onto the steel and follow it with a cut off wheel:
You can get most of it that way, for the little things like the curve at the top in this pic:
I use the bench grinder, just grind off all the white paint: