As he builds and fixes the museum’s 70-plus hands-on exhibits, Narf designs experiments, solves puzzles, and, well, tinkers — all in the service of physics education. In 2016, more than 4,000 schoolchildren visited the free museum to spin bicycle-wheel gyroscopes, crank electrical generators, and yank on pulleys. Each exhibit demonstrates a physical law, explained by printed placards or in person by Narf and his student docents.