Captain Americas shield is made of a unique Vibranium-metal alloy that has never been duplicated. The shield was cast by American metallurgist Dr. Myron MacLain, who was contracted by the U.S. government to create an impenetrable substance to use for tanks during World War II. MacLain was never able to duplicate the process due to his inability to identify a still unknown factor that played a role in it. The shield is circular, relatively lightweight, and made of the nearly indestructible Wakandan metal, vibranium, in the Marvel Cinematic Universe (MCU) franchise. It is created by Howard Stark and given to Steve Rogers during World War II. Vibranium is much stronger and more stable than any other metal, allowing weapons made of the metal to slash cleanly through armor. In the comics, Cap’s shield has had many different compositions, including steel, vibranium, and adamantium. However, in the MCU, the shield is made of pure vibranium.