NeverBlender is a set of utilities for Blender 3D modeling and rendering package. Currently, the most prominent tools in the package are nwnmdlexport, which will export Blender-created objects to NWN ASCII .mdl format, and nwnmdlimport, which will import .mdl geometries and associated textures into Blender.
The featureset is fairly complete and it's easily extensible. The only major features missing are animation exporting and particle effects.
The project is currently unmaintained and doesn't work on modern Blender versions. However, the code is available on GitHub and maintainers are encouraged to further develop it.