[Jeba]

Hello. I promised to help a friend out with some patches for his floor pan in his Camaro but turned out the entire rear passenger seat foot well was rusted badly.
Replacement panels are hard to get over here so he asked me to try and make one.
It is basically a square bowl about 18 x 18 inches with two corners very rounded. The idea is to shape the tall rounded edge and corners, and then roll a few beads in the flat area for rigidity.

I hit a few problems with the panel trying to make it in one piece. I tried tucking and shrinking the rounded corners but ended up with cracks after a lot of tucking and hammering. I did the tucks with a tucking fork but after a while, the tucks did not seem to hold and leveled out the previous tuck with the next. Otherwise the bowl seemed to come along okay until the corner sort of work hardened or I shrunk it in a bad way.

What is the best approach? The bowl is about 6-7 inches deep. Should I have used a shrinking stump? Or is it necessary to heat the metal? The metal I believe was 18 gauge.

This is the first time I have had to try shrinking such a wide "flange".
I would like to make it in one piece if possible.

Thanks!