On an undulating stretch of California coastline, a hidden guesthouse runs free of the grid. "The house is elemental," says project architect Dan Weber of Santa Barbara–based firm Anacapa, who collaborated on the project with designer Steve Willson. "We endeavored to make it out of materials that would wear and take on a patina over time, so they could feel like part of the landscape." Unfinished steel, board-formed concrete, and glass continue inside, where rich black walnut—used for ceilings, cabinetry, and furniture—provides an inviting contrast. "On a foggy day, you want that feeling of warmth around you," says Margaret. Brass fixtures complement the deep-hued wood.