Starting with an uncovered ancient cement patio surrounded by a C-shaped stone house in S. Austin and a request for an outdoor shower, I was able to not only give them a shower, but also a rear entrance trellised patio with steps and planters using stone that matched their existing house.  The ferrocement wave forms open to the sky as well as the yard.  Inside are a 4-foot stone bench, colored mirror insets, a built0-in sink that tapers into wavy shelves, and hooks with fish shapes.  The grey water empties into the yard.