Also, although he was an airmail pilot, he refused to carry souvenir letters on the transatlantic journey, insisting that every spare ounce be devoted to fuel. The fuselage was made of treated fabric over a metal tube frame, while the wings were made of fabric over a wood frame. The plywood material that was used to build most of Lindbergh's plane was made at the Haskelite Manufacturing Corporation in Grand Rapids, Michigan.[12]