An idea for a printable prosthetic hand, first dreamed up when Eric Ronning was bored during an entry-level freshman engineering course, has now been recognized with a national inventors prize for the UW-Madison junior, who?s also parlayed it into a start-up company. “I feel like you could change the world with this idea,” said Ronning, a mechanical engineering major from the Chicago suburbs, in a university release. “And that?s what keeps me going.”