Moreover of creativity and intuition, the design of products lies on a rational identification and exploitation of Non-Functional Requirements (NFR) of Products. Indeed, the preliminary design must follow strictly the fundamental attributes that constitute true restrictions to an optimal solution. These NFR are not directly operationalizable and it is necessary to define particular mechanisms for operationalizing each of them. The elaboration of a basic preliminary design is not a common activity in the product's lifecycle. Not having a preliminary design miss the possibility of taking early advantage of the information related to NFR, obtained in the definition phase of a solution (product). This omission delays the incorporation of fundamental attributes, troubles the design optimisation process and may increase the design costs. Some questions to be answered by this article are: May NFR determine a preliminary design as a basic design model for products? May the early elaboration of the preliminary design model contribute to reduce the costs and optimize the products' design? NFR determine particular aspects of the preliminary design. This approach was tested for several kinds of products, in particular software products: individual and product lines. The main contributions of the preliminary design are the early taking advantage of the definition phase knowledge of a product, in particular of its NFR; the introduction of preliminary design models in order to contribute to control the design cost, using early fundamental design attributes. A preliminary design model ensures fundamental attributes of the product design and guides the optimization of this one.