Today, the development life cycle of 3D User Interfaces (UIs) mostly remains an art more than a principled-based approach. Several methods 1,3,7,8,9,10,11,15,17,18,19] have been introduced to decompose this life cycle into steps and sub-steps, but these methods rarely provide the design knowledge that should be typically used for achieving each step. In addition, the development life cycle is more focusing directly on the programming - sues than on the design and analysis phases. This is sometimes reinforced by the fact that available tools for 3D UIs are toolkits, interface builders, r-...