The ancient process of making metal leaf was difficult and time-consuming. Craftsmen would place a small piece of metal into what was called a goldbeaters skin. This skin was made from the outer membrane of a calfs intestine, which is transparent, elastic and will not rip or tear during the long hours of hammering required to create a piece of leaf. Today of course, the process is made far easier through the use of computerized beating machines. But even with modern equipment, the creation of metal leaf is tricky and very time-consuming. Though the core difficulty remains. Each piece of gold must be flattened, cut and flattened again. To create a final sheet of flattened material this may have to happen hundreds of thousands of times. This is why even today there are only a few manufacturers around the world who can produce high-quality metal leaf.