Timo Arnall, who, together with Jack Schultze brought us a touchless Rube Goldberg machine based on RFID back in 2009, has teamed up with Jorn Knutsen and Einar Sneve Martinussen to produce Immaterials: Light Painting Wi-Fi, which is a project that visualizes wireless network signal strength in city areas using a custom-built 4-meter measuring rod equipped with LEDs and conventional light painting techniques. [via Core77]