The light switch on the drawing board.
A + B are the connections to contacts
C are the contacts at the top of the slope
D is the plastic housing with the slope.
E is the little ball. 1 is the position in rest, 2 is the position when tilted.
Actually the switch is pretty simple. Inside a plastic housing there is a small steel ball, located down a slope. This ball can freely roll over the slope. When you twist your wrist towards you, while your arm is hold roughly parallel to the ground, the ball rolls over to the top of the slope. At the top of the slope there are two contacts. When the ball is at the top of the slope, it connects the contacts, so the electric circuit is closed. The light will turn on.