Artificial rock formations can look great in large backyards. It is certainly easier to make your own rock formation than bringing in rocks to create a rock formation. The key to an artificial rock formation is to make sure to get the texture and color as accurate as possible. Although they may seem like the last steps of the process, they are steps you should not skip over, because it would be a shame to build an entire rock formation that ends up looking like a cement structure.
Create a basic shape of the rock formation by driving rebar into the ground and bending it with a bending tool to create the skeleton of the rock formation. The vertical rebar, once bent is cross braced by laying horizontal rows of light rebar at the point where the bars cross.
Attach heavy gauge plastic sheeting behind the rebar and use wire ties to pull the plastic up.
Use chicken wire to shape the surface of the rocks and details into the rock formation.
Apply concrete to the structure using a trowel. Build a layer of concrete at least 3 inches thick to cover the wire and rebar.
Spread the sand aggregate mixture over the concrete base.
Wait until the concrete is partially cured, and then cover the large flat areas in the rock formation with wrinkled aluminum foil. Let it stand for about five minutes and then remove the foil. This will add texture to the rocks.
Spray on the stain or paint for the rock formation. Make sure you choose a color found in nature to make it look as believable as possible.