“How do you bring the desert into the casino?” asks architect Drew Gregory, of the firm assemblageSTUDIO, led by Eric Strain. The answer? One thin piece at a time. Working with Benchmark Development, the firm has managed to turn the eco-friendly rammed-earth wall—a wall composed of about 94 percent ordinary dirt, 6 percent cement and a hint of water—from a three-foot behemoth (see: Springs Preserve) to a svelte three-inch work of art. The layered sand-colored wall—as thin as you’ll find anywhere—hangs, in dozens of square-sized blocks, outside the Border Grill at Mandalay Bay. It’s as solid as concrete, and as whimsical as a painting.