How to make celing tile montains?

I have "what I did's" at:

Just scroll down the page


Thank you if you visit
I just started using ceiling tiles for rocks formations. I'm modeling the Southwest and they're perfect for the sedimentary look. Here's a pic with just the base color on. I glued the pieces together with Liquid Nails for Foam, then shaped/scraped with a fork. I first primed with KILZ primer and filled in some holes with joint compound, then covered with a base coat of latex paint. Shading and weathering comes next.
I used this method a couple of times due to weight restrictions. It excels at keeping the weight down while looking very "heavy" and real.

I did develop a fine tuning technique to really bring out the fine detail of layered sandstone. Once you are at the stage shown in Doc Holliday's pic, slap on a thin coating of plaster, let it set up just a bit, then brush it with an old hairbrush (the kind with lots of bristles). This gives the plaster hundreds of tiny grooves that look very much like inch thick layers. It doesn't really show up in pictures, but in person it's amazing. And a lot easier than using a knife (or a fork, which is clever).