A standard framing square lets you calculate basic cuts on common, hip, and jack rafters, but the tables on the Chappell Master Framer let you calculate cuts for all sorts of complex roof frames. That includes all cuts needed for an unequal pitched roof, as well as for a hexagonal or octagonal roof. The stainless-steel tool comes with a detailed instruction book, and its inventor says an experienced framer can become proficient using it in a couple of hours. An 18-inch-by-24-inch model costs about $120, and a 12-inch-by-18-inch one costs $85.

Chappell Universal Square & Rule Co., 207/935-3720, chappellsquare.com.