ixForten4000 form-finder is able to relax a mesh into a shape with assigned prestress and/or tension. Not only the membrane can be specified but also the supporting steel,wood or concrete framework. The system uses a range of technologies to produce the final result based in a “self stressed” model. Membrane stress state, cable tension, beam bending moments and stiff plates a part of this global equilibrated system. ixForten4000 has a number of Form-finding streategies for this purpose: Linear FDM : Linear Force Density method controlled by the force density value C. The mesh is relaxed and all links end up with a positive tension proportional to the C value. Non-Linear FDM :Non linear force density method enables constraints like fixed force, fixed length and fixed unstrained length on the links. Brute Force FDM : The Brute force FDM solver enables fixed force and fixed length links using a sparse matrix solve technology that outperforms hundred of times the speed on the classic Non-Linear FDM solver.URM Solver: The Update Reference Strategy is a technique developed by prof. Bletzinger and enables direct form-finding over triangle and quad meshes. IsoTropic or Anisotropic membrane stress state can be specified and so natural minimal surfaces are easily shaped with this technology.