
this 2 files must be placed in the script startup folder or run each time you are going to use the exporter.
as this files create all the materials and maps plugins.
copy:
Gtools_PBRT_Maps.ms to -> C:\Program Files\Autodesk\3ds Max 2010\Scripts\Startup\
Gtools_PBRT_Materials.ms to -> C:\Program Files\Autodesk\3ds Max 2010\Scripts\Startup\

then just run Gtools_PBRT_Exporter.ms