Abstract: Positive wax models are disposed on carriers in a casting frame so that the widest cross sections are in a common plane, vertical fitting pins are provided, and the frame is filled with silicone to the level of the plane to form a first model. The surface is then coated with silver, electroplated with copper, and reinforced with synthetic resin to form a first electrode, which is removed from the first model. The first model is likewise removed from the frame and oriented by means of the fitting pins in a casting frame filled with hardening carrier mass to the plane of the widest cross sections. The carriers and molding mass are then removed to form a second model. The surface of the second model is then coated with silver, electroplated with copper, and reinforced with synthetic resin to form a second electrode, which is removed from the second model. The electrodes are then used to erode respective opposite sides of an erosion body to form the spare parts.