Dunham has harbored a love of helicopters since childhood and is fond of building and flying his own kit helicopters from Rotorway helicopter kits. At the time he finished writing his autobiography in June 2010, he was beginning to build his fourth kit. He is also an aficionado of muscle cars and Apple, Inc. products. According to the July 16, 2012, television documentary "The Batmobile", Dunham owns the original Batmobile used in the Tim Burton film "Batman", which he had outfitted with Corvette engine to make it street legal.