LAKE ELMO, Minn. — In Minnesota, the coolest guy on the block is not the one with the Corvette. It’s the one with his own personal Zamboni. Jim Leonard is that guy, with a 40-year-old personal-size machine that makes him a rock star in his hometown of Lake Elmo. “It has been a dream of mine since I was 5 years old,” Leonard said as he climbed into the driver’s seat and twirled the wheel controlling the scraper blade. The machine is one of the strangest contraptions ever built.