In forming a can body by processing a cup-shaped in-process material with a punch and a die, the die is not heated when the forming process is not carried out, and the die is heated when the forming process is carried out. Looked over the longitudinal and vertical cross-sections, this fabric is in a V-shaped arrangement, with high degree of filling as well as the desired bulkiness and uniformity. The extracted casings are thereby marked with a unique weapon identification number, which can easily be read by standard forensics methods.