pyFormex is a tool for generating, manipulating, and transforming large geometrical models of 3D structures by sequences of mathematical transformations. Thanks to a powerful (Python based) scripting language, it is very well suited for the automated design of spatial frame structures. It provides a wide range of operations on surface meshes, like STL type triangulated surfaces. There are provisions to import medical scan images. pyFormex can also be used as a pre- and post-processor for Finite Element analysis programs. Finally, it might be used just for creating some nice graphics.