I would like to add this, start with some part unseen. An inside panel, a floor or something like that. The first panel you cut, to weld in, is not going to fit. probably the second panel is not going to fit, but it will fit better.
The first panel I replaced was on a rusted wheel barrel. Yes, it was ridiculous to repair the pan on the wheel barrel, instead of replacing the wheel barrel, unless you count the experience gained. The second set of panels, another wheel barrel. Did I mention we use the wheel barrels on a horse farm for just moving manure?
Now, I am working on the floor of a Datsun pickup,
This is trial fitting a piece for the floor.
This is test fitting a second piece for the floor, the main floor piece.
Along the way, I made this template,
I cut the two piece to fit together.
Kick panel cut.
Welded them together.
Along the way I made this simple die.
To make this dimple for a body mount bolt.
And I had to make another piece for the wheel well.
Any way, here is a picture of the floor piece ready to put in the cab. I think.
This is a project I am currently working on, I am not sure how it will turn out until I am done.