Aluminum

The "Alligator" amphibian tractor is the progenitor of all amphibian assault vehicles used since 1941, a pioneer venture both in its design and the materials used in its construction. Donald Roebling, a grandson of Colonel Washington Roebling (designer of the Brooklyn Bridge), built an amphibian tractor to rescue victims of Florida's devastating hurricanes (particularly those in 1926, 1928, and 1932 that hit southern Florida).

This 50,000-ton die-forging press is among the largest fabrication tools in the world. It was designed and built for the U.S. Air Force by the Mesta Machine Company of Pittsburgh, following the discovery of a 30,000-ton press used by the Germans in World War II (later acquired by the Soviet Union). By 1950, a Heavy Press Program was organized to establish a self-sustaining industrial base for a press capable of producing large forgings and extrusions for the United States. The 50,000-ton Mesta press was one of the first built under this program between 1952 and 1955.