"Heinz Isler's involvement in the development of the design for the "Steinkirche" ... could not be more different from that of the church at Lommiswil. ...[A] competition... [was] won by Werner Schmidt... Isler was consulted as an expert in shell design and construction. To understand the structural behaviour... and, in particular, the effect of these glazed openings, Isler returned to his tried and tested methods using physical models. ...To transfer forces across the openings in the shells, the sides of the cut were to be linked by steel bars, whilst the glazing was installed in the plane of the cut surfaces of the removed wedges. ...Isler made plaster casts and Styrofoam models... From these he cast thin latex rubber shells complete with the cut-out openings and with flexible cords linking the two sides... These rods were disposed in a diagonal "zig-zag" configuration similar to that of the lacing on a traditional leather football or shoelaces... When the rubber surface was loaded it was easy to see how the flexible cords behaved. ...compression near the top of the ovoid forms and in tension towards the base. In the final scheme the forces are carried by hightensile bars... To enable the same anchorage detail to be used in all locations, Isler developed a "brush anchor"... Heinz Isler's... method for determining the shape of his shells was to accurately measure a plaster cast of the form."