An embossing hammer is meant to shape metal from the inside out. They come in many different shapes and sizes, depending on the shaping desired and the size of the project. An embossing hammer stretches metal as it is used, as the metal being beaten curves up the side of the hammer, known as "raising."
Often used by metalsmiths on sheet metals in jewelry making, embossing hammers are also used for repossé. Yes, they come with different textured heads. Embossing hammers are most often used on sheet metals, not wire - but good idea.
Answer contributed by Dale "Cougar" Armstrong