Novel conceptions of structures consisting of spatial formations of struts and cables present a uniquely defined morphology and structural performance, and offer opportunities for innovative applications in building design. A common feature of these structures is that their spatial geometry is not “a priori” given. This paper is focused on a specific type of cable-strut structure that occurs from the assembly of self tensioned cable-strut modules The spatial configuration of these structures is very complex and necessitated the development of elaborate geometric algorithms that permit the generation of their formal geometry in a virtual 3D environment. To facilitate both the design and the construction of such structures, a spatial visualization system, which integrates a) algorithms for initial form generation, b) geometric parameters that simulate construction stiffening processes, and c) appropriate structural analysis methods, has been developed. The structural organization and parts of this system are presented in this paper. The system renders feasible the exploration of alternate geometries with various levels of pre-stress and displays initial and final configuration of the structure. It also allows for structural analysis data visualization. Examples of projects designed with the assistance of this system are included and discussed.