The French branch of the Graffiti Research Lab developed the NTQ (Near Tag Quality) printer using Arduino, Solenoid and seven spray cans. The project took two months to complete and cost around €200. Their goal was to build the device and then opensource it.
The single spray system uses a solenoid valve to control the flow, and a number of transistors to receive voltage from the signal issued by the Arduino board. The Arduino is programmed so the cans spray out a chosen sentence. The NTQ was shown during the This Place Has No Atmosphere exhibition at the IMOCA Dublin in September and will be at the Eniarof festival in France in December. It can be seen in action below: