Ron, Im using a combination of a few different mediums, Acrylic paint (like for Canvas) Its thicker and can add texture. pastel chalks. I sand them into small piles and create the color I need, I dry brush that on as well as hit it with a Dab of water for different effects. Bare in mind im making all this up as i go along, I have never seen this done before so its alot of trial and error. Nice thing about acrylics and chalks, you can wash it off if it looks to bad. To seal it i use plain old Testors Dull Cote. I tried some more pics but i am a Victim of crappy Lighting. I have not even touched the Tracks yet as well as most of the Tank. Looks much richer in person.

Semper Fi!