I make these guitars from old galvanised corrugated iron sheets found in sheds and farms. Some of it can be about 100 years old.
I roll the sheets flat and , because the steel is stiffer and thinner than other types, the guitars are very light weight for a metal body. For instance the single cone weighs just 3.3 kilos (7.2 pounds)
The guitar on the right is actually a tricone which weighs just a bit more.
You can have both single cones and tricones with traditional “F”holes, 3 slots per side or grilles and my special domed tricone coverplate.