This paper introduces the different problems related to the choice of rapid prototyping processes, in order to produce some particular parts or tools. Very often, people have no time to test different solutions or they have not experts for a comparative evaluation of the different possible industrial technologies. Of course, one could imagine that it is very difficult for somebody to know all the present technologies at a time, and to evaluate a multi-criteria choice. Another important aspect is that tests are time- consuming and money consuming. The knowledge-based system presented in this paper will propose, from the specifications (numerical model quality, delay, cost, material, quantity, etc...), different alternatives of rapid prototyping processes, which will be discriminated and optimized when considering a combination of the different criteria of the specifications. The proposed system is based on actual machines and technologies, which are really accessible in the company or outside (subcontractors or laboratories), for the realization of each step of the complete processes. In the following paragraphs, the chosen software solutions for knowledge modeling and process choice will also be presented.