Owens, 31, began building an 18-foot-tall, one-ton prototype at his home in Wasilla, Alaska, in 2004. Working without blueprints, he first built a full-scale model out of wood. Moving on to steel, he had to devise a hydraulics system that would provide precisely the right leverage and range of movement. He settled on a complex network of cables and hydraulic cylinders that can make the mecha raise its arms, bend its knees, and even do a sit-up.