pyFormex is a tool for generating, manipulating and transforming 3D
geometrical models by sequences of mathematical operations.

Unlike traditional CAD systems, pyFormex uses a powerful scripting
language as the basic user input method, making it very well suited
for automated and repeated (parametric) design procedures. 
It provides a wide range of operations on surface meshes, like STL
type triangulated surfaces, and FEA meshes or CFD grids. 

There is also support for Nurbs curves and surfaces