Monostatic bodies, such as the Gomboc in the picture, will roll around (like an inverted turtle) until they find the one orientation in which they are stable. (These objects are different from something like a weeble, or weighted top, in that they have uniform density).
This suggests a new form of domestic lighting. In today’s invention, an array of gombocs would be located on a metal tray. Each would contain a circuit with a small watch battery, an led and a pair of slightly protruding contacts at the stable basepoint on the ‘underside’. These contacts would act as a switch which would be closed by each body contacting the tray as it rolls through the stable position.
Any movement of the tray would set in motion all the oscillating gombocs, switching on and off their leds at the rolling frequency. This would produce an interesting light pattern in response eg to pulling a chair or a drawer out…or opening a door. Using bodies of different sizes or densities would add even more variety to the lighting patterns. Translucent bodies with embedded lights would be particularly attractive.