I'm about 70% done with a rather large desert dio. Nearly all the materials
I've used are natural and FREEE! Of course you have to live in an area (the country) where they are readily available.
I've gone a little over the top and built a permanent dio in my family room. The base is made from 2X4's covered with 1/2" plywood. Elevation changes are both structural and "Blue" foam insulation board. Rock out-croppings are a unique sandstone found in the neighborhood that are the closest thing to Mountains in Minutes you've ever seen, but natural. I did finally break down and bought some Studio 56 Palm Trees, then started scratch building palms from Sculpey and silk leaves from an artificial plant.
If any of you members know how to post pictures, I'll send a couple work in progress shots. I'm really a computer amatuer.
" In an earlier life" I was into model railroading so the scenery part is not too tuff. I've white glued some of the sand down (4 or 5 sq. feet). but most is still loose for final positioning of the vehicles and figures. My real intention is to have a realistic place to display my works that adds context to the models. I had an extra 5' of space for a town scene but I had to give the kitchen island counter back to my wife so that idea went into the dumpster (for now anyway).