I saw a 30mm thick, frame-shaped profile in one store. They attached the sheet to this profile, gradually warming and hammering and bending both sides.I got the pain in my hands just from the this imagine. But I believe the result had to be perfect. Work for slave ....
If you will use a powerful pneumatic riveter or you make a tool into Pullmax, you can do anything.
You must will do steps move slowly. It is feasible. See You tube from Neil.
Historical Note: Autogen - Oxygen and Hydrogen was used in 1801 !!!! Vikipedia.
Nothing new thing.