Thanks Dunnah01,
Just basic panel beating/restoration process.
1. Decide how far you need to cut back to get rid of external & internal rust.
2. Think about how you are going to form the panel. 1 or 2 pieces depending on your skills & equipment.
3. Make some cardboard templates for the pieces you want, these can also be used to make sure the contours are correct when forming the panels & to help line up before welding.
4. cut your pieces from sheet steel (same thickness or slightly thicker in some places to add strength.
5. Form them up, you can use jenny/rollers, folders, strecher/shrinker etc if you have the equipment or good old panel beating. A vice, tubes, wood, sockets, anvil, pliers, hammer & dollies or anything else that you can use to shape the metal to whatever you want. You can also stretch metal by keep hitting it, or shrink it using peening method (sharp edge of a panel beaters hammer) or if you have oxy acetelyne, heat it up to cherry red and use a hammer & dolly.
6. one you have all your pieces cut & formed, tack them in place making sure the surfaces are as flush as possible to reduce steps when grounding welds down.
7.When you are happy everything lines up and other parts/panels fit then weld them up an inch at a time to reduce heat distortion. Make sure you get good penetration as you will be taking the top off so you need weld all the way through the panel.
8. knock the heads off the welds with a grinding wheel (dont go too mad) then change over to a grinding disc (36 to 80 grit) and sand the welds flush to the panels trying not to take too much out of the sheet metal - especially Fiat as it is not that thick.
That's it.
If I get a chance I will take a few photos of the next piece I do.