Which type of hammer is primarily used to shape or form metal?

The type of hammer primarily used to shape or form metal is the ball peen hammer. This hammer is specifically designed for metalworking tasks. It features a rounded end, known as the peen, which is used for shaping and forming the surface of metals. The flat side of the hammer is typically utilized for striking, while the peen can be employed for tasks such as riveting, establishing a rounded edge, or shaping metal components.

In contrast, a claw hammer is mainly used for driving and removing nails in woodworking, a sledgehammer serves as a heavy tool for demolition or driving large stakes, and a rubber mallet is designed for softer strikes to avoid damage to surfaces. Each of these hammers serves distinct purposes that do not align with the specific needs of shaping or forming metal, making the ball peen hammer the most appropriate choice for this function.