A pummer is a BEAM robot that absorbs solar energy during the day (by charging up a large capacitor or rechargable battery from a solar panel), and releases it during the night, usually by blinking one or more LEDs. Think of it as a robot “plant”. The trick here is to get a circuit that is energy efficient (so can blink the LEDs for as long as possible once it gets dark), and blinks the LEDs in interesting ways.
This a pummer that I built. It’s a dual LED pummer, based on a bicore circuit using a 74HCT240 chip. The circuit is described at the Solarbotics site (see schematic for a similar design that uses recharable batteries in place of the capacitor).
The frame of the pummer consists of three hard drive spacers; two for the base (a thin dark one on top of a larger aluminum one), and one placed vertically. Both the HCT240 and the 1F storage capacitor just fit inside their respective rings, which inspired the design.
The LEDs are super-bright blue and green. Because these suck up a fair amount of juice, this pummer only runs for about an hour after dark.