If you're looking for fake STONES (and not brick) you can use that foam sealant in a can (for weather sealing around pipes and windows), but be careful. A little goes a long way as it can expand up to 10X before firming up. Once set up, it can be painted to look like stone very convincingly. We used it to make a stone fireplace on our set for DON'T DRESS FOR DINNER. It comes off with a scraper or putty knife. A little sanding and a new coat of paint and they're back to being plain ol' flats.

Was it brick or rock walls you wanted? For rock we have used thin pieces of stryrofoam packing. Just paint it then rip it into a variety of shapes and sizes. Apply with low heat hot glue, pop off with a putty knife.

ANgel

Stone can be done in a number of ways. You can take sheets of white styrafoam and carve the shapes of the stones into it with a Dremel tool and paint as needed. This way you end up with big sheets of stone that you can tack to existing flats.

Another options is foam rubber, which can be torn to create rough stone like surfaces and then glued to a backing.

I saw a great way to do bricks once. Start with a luan backing painted black. Then take asphalt roof shingles and cut brick size pieces out of them. You can get red roof shingles, or paint 'normal' collered ones. You then glue these onto the backing in a brick pattern. The result is a little heavy but it looks great.

Dan

nice site  ty   want to do a fake rock wall in my living room   these ideas are great

Why do 3D when paint works just as well? Use a square sponge, dip in paint, squeeze until almost dry and press to flat.  Do the same thing in a highlight color. Then you only need to accent paint the grout!