Blueprints of the intended structure are studied and the copper plates marked off accordingly. Copper plates are bent to prescribed angles, holes are drilled and edges smoothed. The copper plates are cut either mechanically or by means of a gas cutter. The copper plates are then straightened, bent, rolled or dished to the required forms. The shaping is done with heavy machines working on the cold copper plates. Hot processing is sometimes required when difficult angles have to be shaped. Holes for rivets and stays are drilled into marked-off positions. Overlapping sided ar ecompressed together.