The method involves connecting a foil (1) to be formed with a crank shape having an opening. An area of the foil is physically and chemically modified. The foil is inserted with the connected crank shape in the opened forming tool, which has a base plate and an oppositively lying counter tool. The foil is removed from a modular counter tool connected with the crank shape. The foil is selected such that it consists of plastic or mixed plastics waste.