Manufacturing process for hollow plunger rod

A method of molding a plunger of a drug delivery device, the method comprising:

• loading a plunger body into a cavity of a first molding tool of a molding system, the plunger body including an inner wall defining an axial chamber, an outer wall, a first end, a second end opposite the first end, wherein the cavity at least partially defines a first molding portion, a middle portion, and a second molding portion;
• coupling a second molding tool to the first molding tool loaded with the plunger body 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 of the coupled first and second molding tools and into the first molding portion and the second molding portion to form an overmolded plunger body, the overmolded plunger body including a head coupled to the outer wall and at least partially surrounding the first end of the plunger body and a foot coupled to the second end of the plunger body.