Shells and tension structures (cable nets or fabrics) are beautiful structural elements that provide a very lightweight organic shape with a visually clear structural language. When it comes to creating these, however, specialized tools are required since the underlying math is anything but trivial.
If you want to work with shells or tension structures, try out these approaches:
- Membranes24.com – This site provides a free online service for form finding of tensile fabric structures. They have several basic shapes where you only have to provide node locations. As an added bonus, for some of those shapes, cut patterns can be downloaded. As can be expected, the free version does not allow for input of material properties. For added functionality, a plugin for Rhino is offered that provides more design freedom.
- SoapSkin Bubble – This is a SketchUp plugin that takes a closed loop of 3D edges and then fits a soap-skin type shell between those. Beyond this basic functionality, fabric property ratios can be defined and a pressure can be applied (try a very large one for an interesting effect). See the last image in this post for an example of a shell.