In a method of producing a stacking projection and a corresponding tool a mandrel as part of the tool is inserted into a cup, wherein the mandrel comprises a receiving recess. The bottom part of the cup is then supported by a supporting tool and a collet is assigned to a region of the cup where the stacking projection is to be formed. Thereafter, at least a part of the collet is pressed radially inwardly in direction to the receiving recess such that a portion of the cup wall is pressed into the receiving recess to form the stacking projection. Simultaneously, the height of the cup is reduced by displacing the mandrel and/or the supporting tool with respect to the other in axial direction. Finally, pressure applied to the collet is released and the cup is removed with the mandrel from the collet and the supporting tool. By such method and corresponding tool the stretching of the wall material is avoided as well as any defect of an inner layer of polymer of this material and simultaneously the method of production and corresponding tool are simplified or of simply construction and can be used for high production rates of corresponding cups.