To switch on the Watt? Light, by Paul Cocksedge (designed in 2003), you need to draw a pencil line on a sheet of paper in order to complete the electric circuit. The switch is based on the natural conductive properties of the graphite found in pencils. Rub the line out to switch the light off.

Video from design-unfolds.

Seen at the Touch Me exhibition, Victoria and Albert museum, London, until 29 August 2005.