Abstract: An apparatus is disclosed that includes a printer cartridge having a cartridge barrel for containing print material, an extruder having a nozzle and a lever arm, the lever arm including a plunger, the plunger having an inlet port, and a pneumatic system including a pneumatic piston, a solenoid valve and a Y-connector, wherein the pneumatic piston is configured to receive pressurized air from (1) the Y-connector to lower the lever arm to align the inlet port with an entry point of the extruder enabling print material to flow into the extruder through the inlet port, and (2) the solenoid valve to raise the lever arm to misalign the inlet port and the entry point to prevent additional print material to flow into the extruder. The apparatus further includes a build platform, and a plurality of rods and screws for guiding the extruder to dispense print material on the build platform.