The best tips for making fake rocks include getting some real samples to look at for realistic shapes and color patterns. Whether the artificial rocks are for retaining walls, ponds or flower bed borders in yards or for another purpose such as a rock climbing wall or as scenery in a play, a few materials and a little experimenting with different techniques can produce good results. When making these rocks, perfection certainly shouldn't be the goal, as the real kind are full of imperfections.
Foam covered with chicken wire then with a cement mixture can be used to make large fake, or faux, rocks. A wheel barrow will hold a lot more of the mixture than most other containers will. Either a foam cutter or a box cutting tool can be used when making rocks out of spongy foam. A wire cutter is also needed; the wire helps stabilize the foam and gives the piece structure. When cutting the foam, it's quite fine to make uneven, jagged cuts, as real rock often has the same look.
Another way to make fake rocks is to use roofing sealant foam. This is a much faster method of making fake rocks than the foam, chicken wire and cement procedure as it involves simply spraying the sealant material onto a piece of cardboard. The cardboard should be fairly thick to serve as a base for the roofing sealant foam. The sprayed sealant should form a rock-like blob of the desired size and shape on the cardboard. After it dries, it can be painted either with layers of spray paint or with different acrylic paints sponged onto it.
Different neutral colored paints can be experimented with to create realistic looking finishes for fake rocks. The great thing when painting fake rocks is that there really can be no mistakes or way of ruining them because more paint layers or speckles can always be added. Sprinkling drops of paint on the fake rocks, letting them dry slightly and using a soft brush to blur them is just one of the techniques that can be used when making fake rocks. To get the speckles looking as realistic as possible, having a few real rocks of this variety on hand can be a good idea.
For fake landscaping rocks and others that will be outside, spraying a good, weatherproof clear sealer on top is usually a good idea. Even when making fake rocks for indoor purposes, spraying a clear acrylic sealer as a final coating can help the finish last longer. Protecting all types of do-it-yourself rocks with a sealer may take several coats depending on the brand.