Brothers Massoud and Mahmud Hassani grew up in Kabul, Afghanistan, knowing that one wrong step could end their lives. "When we walked to school, we had a special path to follow—otherwise we would end up in a minefield," Massoud says. Mines are cheap to manufacture and deploy, but slow and expensive to remove. An estimated 110 million land mines litter the globe, killing 15,000 to 20,000 ­people a year. Living among them "becomes like a mental disorder," Massoud says. "The fear is on your mind all the time."

After the Hassani family relocated to the Netherlands, the brothers created an ­anti-mine device based on a ­wind-powered tumbleweed toy they'd built as children. The Mine Kafon (kafon means "explode" in Dari) could roll through a minefield, detonating any mines it crossed and thus marking out a safe path. Though more conceptual than practical, it became a hit; New York's Museum of Modern Art even bought one in 2012.