Jennifer Siegal first grabbed our attention in 2006, as a prefab pioneer with an abundance of percolating ideas. Fast-forward, and the 44-year-old's eco-friendly visions are coming to fruition. Her first completed house sits near Joshua Tree National Park, in southern California. In April, a family moved into a 100% off-the-grid house she designed in Big Sur. And she and her students at the University of Southern California are now tackling the architectural design of food trucks (a nod back to Siegal's days of slinging hot dogs to put her-self through school).