Some more wonderments in honor of the Alan Turing centenary: Jeroen van den Bos and Davy Landman from the Centrum Wiskunde & Informatica in Amsterdam have created a working Turing machine out of Lego. It is both inspired and an inspiration:
Our LEGO Turing machine uses a tape based on a classic interpretation of computer memory: switches. Additionally, it uses a light sensor to determine the value of a switch: if the switch is on, the sensor will see the black colour of the switch's surface. But if it is turned off, the sensor will see the white colour of the LEGO beam, making it possible to distinguish between the states. Finally, a rotating beam mounted above the tape can flip the switch in both directions.
Alan Turing's original model has an infinite tape, but LEGO had a slight problem supplying infinite bricks. So we chose to fix our tape size to 32 positions.