The ruler is one of those everyday things we use and never really think about it twice. This is how it works and that’s it.

2 designers with the support of udk industrial design department designed the “Electronic Ruler”. It is a 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.

To make it even cooler they placed a set of LEDs under a thin strip of wood-like material that displays the digits.

found here