The shell structures have gained more and more importance in the last few decades. They offer an ideal solution for many engineering problems. They use space more efficiently and can also be built with less material than other types of structures which would cover the same space. Even as early as the sixteenth century some applications of shell structures can be found, e.g., the dome on St. Peter’s Church in Rome. Wide utilization of shell structures did not start, however, until after 1930-1935, when the development of the shell theory gave engineers a more elaborate analysis tool. The preference for shell structures by engineers and architects is mainly because of considerations:      a. The loads are carried mainly by membrane forces, and b. Shell structures offer better aesthetic possibilities, typical thin shell with double curvature. A properly designed shell carries the load mainly by normal forces in the cross section. Moments occur only in certain limited regions, such as the edge areas of spherical domes. For this reason, it is possible to support large loads with small cross sections. Shell structures offer the architect a powerful structural tool because of the possible geometrical variations which help to overcome structural monotony and make a more aesthetic design. Certain types of shells of revolution are preferred mainly because of their functional advantages, e.g., cooling towers, large containers, etc. Even with the above mentioned advantages and with the available mathematical techniques of analysis, shell structures are not widely used because of the cost and time involved building the formwork. A recently developed construction method which does not require this sort of conventional forming opens up new possibilities of shell application. This neve process is a semi-automatic technique known as Spiral Generation. It is the on-site shaping and assembly of mass produced materials by a pivotal boom device to form shell structures suitable as a form. The process continuously heat welds planks of extruded polystyrene plastic foam together to form a monolithic structure.