Infl ated sheet steel units – at fi rst sight it looks like a fanciful novelty but in fact this is advanced technology which has been developed at the CAAD (Computer Aided Architectural Design) department of the ETH in Zurich and has already been successfully implemented. Developed by the architect Oskar Zieta in the year 2006, this so-called FIDU-process – free inner pressure deformation – allows turning fl at metal-sheets into supremely stable three-dimensional elements. Watertight welded double metal-sheet elements are deformed with the aid of water respectively air pressure, applied from the inside. The method, currently in the development phase, is an alternative to similar recently developed processes. FIDU II is the next step in the further development of the researched deformation and stabilization process – towards a larger scale. A large self-designed modular construction has been successfully realized using the FIDU-method. The resulting elements feature surprisingly high efficiency in terms of self-weight / load-bearing-capacity ratio, as well as relatively low processing effort.