Gmsh is a free 3D finite element grid generator with a build-in CAD engine and
post-processor. Its design goal is to provide a fast, light and user-friendly
meshing tool with parametric input and advanced visualization capabilities. Gmsh
is built around four modules: geometry, mesh, solver and post-processing. The
specification of any input to these modules is done either interactively using
the graphical user interface or in ASCII text files using Gmsh's own scripting
language.

pygmsh combines the power of Gmsh with the versatility of Python. It provides
useful abstractions from Gmsh's own Python interface (cad/py-gmsh) so you can
create complex geometries more easily.