Designed by Shay Shafranek and Oded Webman with the support of udk industrial design department, Berlin the “Electronic Ruler” is concept that measures the length of drawn lines no matter where on the ruler you start and stop drawing. It can also measure the distance between 2 points, add the value of different lines and change its scale. Taking a circuit board, he placed a set of LED digits under a thing strip of wood-like material and added a reset button and little touch-sensitive buttons on the side to detect where the pencil is. So how does it work? By pressing the button the digits illuminate and the ruler is ready to go. Passing a pencil along the edge of the ruler will make the numbers go up or down according to the length of the line. Pressing the button again will reset the value. More info here.