Netgen mesh generator
NETGEN is an automatic 3d tetrahedral mesh generator. It accepts input from constructive solid geometry (CSG) or boundary representation (BRep) from STL file format. The connection to a geometry kernel allows the handling of IGES and STEP files. NETGEN contains modules for mesh optimization and hierarchical mesh refinement. Netgen 6.x supports scripting via a Python interface. Netgen is open source based on the LGPL license. It is available for Unix/Linux, Windows, and OSX.