With the use od special templates and diameter/circumference conversion tables, the size of the body of the pipe and of the relative foot are marked on the plate.
After the body shape of the pipe is plotted, it is marked on it the width of the mouth, which is always proportional to the circumference.
The cut sheets are cleaned with the use of a compound of calcium  carbonate and subsequently coated with a refractory paint along both sides that are next to be soldered, in order to protect  the tube and the foot from the risk of overheating and burning during the welding phase.
The cut bodies are then wrapped around a wooden or ironed core shaped like a cylinder (in the case of the feet in the manner of a cone) striking them with a small wooden board.
Regarding the larger pipes, the rolling is carried out with the use of appropriate rolling machines.