Like their creation, identical twins Geoff and Mike Howe, 34, don't like to sit still for long. At age seven, they built a log cabin. Ten years later, they converted a school bus into a drivable, transforming stage for their heavy-metal band, Two Much Trouble. In 2000 they couldn't agree on their next project: Geoff favored a jet-turbine-powered off-road truck; Mike, the world's fastest tracked vehicle. "That weekend, Mike calls me down to his garage," Geoff says. "He's already got the suspension built for the Ripsaw. So we went with that."