The Paper-Duino-Pi is an Arduino shield for the Raspberry Pi. Due to the fact that it is designed as Paper-PCB it is easy to create and one doesn’t need a printed circuit board. All components are standard electronic parts that are easily available at your favorite electronic shop. Plus they are really cheap. All you need are some electronic knowledge and soldering skills.
http://paperpcb.dernulleffekt.de/doku.php?id=raspberry_boards:paperduinopi