There's no better Halloween prop than a carved pumpkin. But Mark didn't like the idea of leaving burning candles unattended in his squash, so he built a battery-powered light source instead. For a realistic effect, he used a timer circuit that produces a pseudo-random timer pattern that makes two ultra-bright orange LEDs flicker, simulating a flame. The power source is four batteries at 1.5V or two 9V batteries wired in parallel for more current and longer glowing time.

For Mark McCuller's instructions on how to create your own "scary pumpkin," click here.

To view a schematic drawing of McCuller's "scary pumpkin," click here.