Gmsh is an automatic 3D finite element grid generator with built-in CAD and post-processing facilities. Its design goal is to provide a simple meshing tool with parametric input and advanced visualization capabilities. It 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 (based on FLTK and OpenGL) or in ASCII text files using Gmsh's own scripting language.
pythonOCC is a 3D CAD/PLM development library for the Python programming language. It provides 3D hybrid modeling, data exchange (support for the STEP/IGES file format), GUI management support (wxPython, PyQt, python-xlib), parametric modeling, and advanced meshing features. pythonOCC is built upon the OpenCASCADE 3D modeling kernel and the salomegeom and salomesmesh packages. Some high level packages (for parametric modeling, topology, data exchange, webservices, etc.) extend the builtin features of those libraries to enable highly dynamic and modular programming of any CAD application.
CAD Scripts automates a range of CAD tasks. It includes text_to_dxf for drawing figures in DXF format by specifying co-ordinates in an input text file.It also includes support for automatically create an entire beam and column structure for FreeCAD or StadPro after entering the specifications of a building.