Vacuum forming tools used for prototyping can be made from a variety of materials. The material choice will depend on the application and will vary in cost. At Kal Plastics, we use wood for prototyping as much as possible because it is the least expensive. However, wood does have some limitations and cannot be used in every application.
Production tools are typically made from machined or cast aluminum which are temperature controlled and last indefinitely. In terms of cost, an aluminum tool is much more expensive than a wood prototype mold and sometimes only slightly more expensive than an epoxy prototype mold. As a rule, the more detailed the part, the more expensive the tool.