Sheet metal can be wrapped around a mold (round, square, or other) and pressed together, though it's not common. I've got a couple diy electronics protected by "boxes" made of U-shaped steel or aluminum with holes cut for the controls. Alternatively, the technique used to create cardboard boxes also works with sheet metal, where you cut the correct shape out and fold the flaps at set locations; of the metal is thick enough you don't need flaps and it'll hold the shape on its own, and if you want to hide the seams better, use compression or notches.