Weekly Creator Challenge #2 Experienced Creators

I managed to make my entire world as a single fbx, textured with your clever MEO atlas image.  This was a very interesting workflow and I learned a lot!  One improvement I would suggest if possible is to add shades of grey, so for instance artists could make grey metal axe blades.  I tried to modify your images myself but was unable to figure it out.  Thanks again for a great tutorial!