President Obama announced Thursday that the federal government was approving a small part of a plan by state and local officials in Louisiana to spray sand on gulf barrier islands to build them up as a defense against incoming oil.

WSJ: Gauging Harm to Ecosystem Could Take Years

Spray from the surf speckled the windshield of his pickup truck parked on the packed sand of Plum Island.

NPR: Excerpt: 'The Assassins Gallery'

But no matter how much energy you put into building a sandcastle, it's unlikely to be as impressive as the structures produced by Stone Spray, a solar-powered, robotic 3D printer that can create entire buildings out of sand.

ENGADGET: Inhabitat's Week in Green: Eindhoven's Evoluon Center, folding compact cars and the best of 3D printing