Three-dimensional models can be made accurately enough by RP methods to evaluate the design process and eliminate interference fits or dimensioning errors before production tooling is ordered. If design flaws or omissions are discovered, changes can be made in the source CAD program and a replacement model can be produced quickly to verify that the corrections or improvements have been made. Finished models are useful in evaluations of the form, fit, and function of the product design and for organizing the necessary tooling, manufacturing, or even casting processes
