The paper presents the outcome of an international research project, aimed at identifying and implementing an innovative approach in computer aided aesthetic design. Despite the availability of sophisticated modelling tools, there are still critical issues to be faced in order to get functionality really suited to the creative users mentality. The presented results are based on the analysis of the design activities carried out with stylists and surfacers (Computer Aided Styling operators) both in the automotive field (BMW, Pininfarina, Saab), and in household supplies field (Alessi and Eiger). Some of the identified aesthetic features, used by designers to judge the shape, are discussed. In particular the free–form modelling tools for curve modification driven by aesthetic properties perception will be presented. Keywords Aesthetic design, aesthetic features and properties, shape perception, geometric modelling.