Developing a Thermoformed product. These patterns can be designed on a CAD system and CNC cut directly from the CAD file or they can be fabricated by hand. The pattern is typically made of epoxy or wood that is both strong and easy to work with.
Mahogany is often the wood of choice.
Often times it is possible to form prototype or even limited production parts off a pattern. This is the point where any fine tuning or adjusting needs to be done. The parts run off a pattern will typically not be of the same quality as an aluminum mold, but should provide enough information. Radii may be added and other fine tuning may be done here. After the pattern is prepped, it is sent to a foundry where a sand casting is made.