Halfbakery: Centrifugal Force Egg Timer
An egg timer is placed (off-center) on a centrifuge. By varying the speed of the motor, you can control the duration of the timer. To enhance visibility, the timer medium (which could be either solid or liquid) is made out of a fluorescent material, and the centrifuge has an integrated black light.
Watch it go around in circles as the grains of time slip away.