This is my Light Printer made out of two old Epson Printers, an Arduino Mega and some wood.
You can write or draw something on an Nintendo DS Screen in Red, Green or Blue. When your done, the Light Printer will fire your camera and start a long exposure. While the printer draw all your points in the dark, the camera takes a long picture. When the printer is done, it will stop the camera and you get a picture with your Light Painting.
Thx to Tobi K. for the second camera