David Jacob Kramer and Michael Schmelling’s ‘Handmade Utopia’ documents the improvised architecture left behind by Northern California’s back-to-the-land movement — cabins, domes and hot-spring enclaves put up by hand in the 1960s and 70s. Published by D.A.P./Edition Patrick Frey, the book treats these owner-built structures as a serious architectural record rather than a countercultural footnote. Few of the originals survive; the photographs are increasingly the only place some of them still stand.