Maps and drawings are created by hand in an aluminum foil sheet. The metal is embossed with a variety of tools to produce raised lines and areas of varying height, texture and width. The maps are labelled with key letters that are identified on the pages preceding each map. The master drawing is duplicated by the Thermoform process to make clear, sharp copies. The 11×11½-inch plastic sheets are bound into volumes with cardboard covers and spiral plastic binders.