A unibody heater module is disclosed having an end cap and a base, wherein the base of the heater canister is filled with a solid-state reaction mixture. Twist-to-activate heater starting functionality is embedded directly into the unibody heater module. A reactive starting pellet is embedded into the upper surface of the compacted solid-state reaction mix. The plunger head of a firing pin passing through the center of an internal metal spacer is held a small distance away from the upper surface of the starting pellet. When the user activated CUI is rotated, the base of a cam pushes on one end of a firing pin protruding through a small hole in the end cap of the unibody heater module. The opposite end of the plunger plunges into the starter pellet so as to initiate heater activation in response to operation of the CUI by the user.