Late in life, he opened an English bookstore in Avignon; before that, in London, he wrote anti-consumerism and anti-automobile books. But he made his biggest mark in New York’s Greenwich Village in the 1950s and ’60s: he briefly ran the Off-Off-Broadway birthplace Caffe Cino, and he devised a kit that lets customers assemble their own harpsichords, enabling the modern revival and spread of the instrument.