As he was walking to a math class during his freshman year at Ohio State University, R. J. Kromer spotted a poster for a student-run team designing a fuel-cell-powered car. He had never built anything more complex than Lego-based robot kits, but he sent an e-mail to the group asking to join anyway. To his surprise, the team members responded immediately. “I thought there would be all kinds of requirements,” Kromer recalls, “but they said, ‘No, just show up.’”