Looking at the Nifskope page it says it uses OBJ files http://niftools.sourceforge.net/wiki/NifSkope/Mesh_import_export http://niftools.sourceforge.net/wiki/NifSkope There is a little youtube video but it is talking about how easy to mod and not import/export and I see niftools is a number of projects doing a google search. I saw a plugin for Blender there for opening nif files, but the skope seems to export to .obj and import as well