This set-up is used to print highly viscous fluids or pastes. From a central compressed air supplyment the air is lead through pressure regulators and 3/2-way valves to the syringes. An electrical circuit containing solid state relais controls the valves. The switch signal is a gcode command that triggeres an unused arduino port (marlin firmware). To insert these gcode commands before and after each travel move I used a postprocessing python script with slic3r.