The undertaken project aims at offering a support for the manufacturing cost estimation of products in the conceptual design phase. This need for dedicated tools for designers emerges from the lack of means to determinate the best technical solution that permits one to save costs and to reach safe quality. The main objective of this tool is to assist the designer in the process of manufacturing cost calculation of a product that is defined by little and inaccurate information in the preliminary design. This paper presents a procedure to develop such a tool.