William Gurstelle is the author of Backyard Ballistics, Building Bots, and The Art of the Catapult. He lives in St. Paul, Minnesota.
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The technology underground is a thriving, humming, and often literally scintillating subculture of amateur inventors and scientific envelope-pushers who dream up, design, and build machines that whoosh, rumble, fly—and occasionally hurl pumpkins acr... SEE MORE