The three pavilion facades for the renovation of the Eiffel Tower's first floor constitute a new challenge in the field of transparent skins with free forms: this smooth double curved surface adapts to the high-performance thermal constraints of a of a unique public interior space. In avoiding the standard facetted solution, the developed project retains the full integrity of the initial Architectural proposal while guaranteeing economic feasibility. Thanks to the optimization of a parametric model, the variable double-curved surface of the transparent skin can be approximated from a quadrangular cylindrical panel surface. This process implies zero torsion at structural nodes and permits the fabrication of structural elements from developable curved sheets by welding thus enabling a standard compact detail.