Interactive designer Lauren McCarthy used Arduino to make a wooly
torture device hat that she calls the Happiness Hat — it has sensors that detect when you're smiling — when you're not smiling, it sticks a metal spike into your head. Here's a short description from her web site:
An enclosed bend sensor attaches to the cheek and measures smile size, a servo motor moves a metal spike into the head inversely proportional to the degree of smile. Through repeated use of this conditioning device you can train your brain to smile all the time.
Happiness Hat web page via
Core77
