A method of manufacturing a plunger of a drug delivery device includes forming a plunger body. The method includes loading the plunger body into a cavity of a first molding tool of a molding system. The cavity is at least partially defined by a first molding portion and a second molding portion. The method includes coupling a second molding tool to the first molding tool to form a plurality of channels defined by grooves in the first and second molding tools, and injecting molten plastic into the plurality of channels to form an overmolded plunger body. The overmolded plunger body includes a head coupled to the first end of the plunger body and a foot coupled to the second end of the plunger body. The foot is at least partially coupled to the inner wall and the head is coupled to the outer wall of the plunger body.