Abstract: Stamping of a layer (2) of package material, such us cardboard or plastics, for forming one or more bending edges may take place according to the invention by a method wherein a stamping tool (8), which is provided with at least two ribs (9a, b, c), is pressed down into the layer (2) and thereby forms the slots (11a, b, c) in the bending edge in one working cycle. The stamping may hereby take place very precisely, and since the stamping is carried out in one working cycle, an unprecedentedlly high production rate may be achieved. Since the stamping tool does not need a lower tool part, but merely a support (10), the stamping may be performed simultaneously with the punching in one and the same working cycle.