Two college friends—and now, design studio partners at Atherton Keener—built a joint residence in Phoenix, Arizona that is the best expression of their appreciation for minimalism. Jay Atherton made the bathtub and sinks by hand, out of marine-grade plywood held together with aluminum spline joints and dyed with Behlen Solar Lux in jet black. To make them waterproof, he coated every surface in a thick layer of West System marine epoxy, popular with builders of wooden boats.