Quote Originally Posted by UncleChester View Post
Cement or grout work well for fake rocks, and should go over wire or plastic mesh form with no problems provided the holes are large enough for it to flow through.
yup, been there. grout is awesome to make "fake rocks"
why not make a negative mold from plaster, then you'll have the rock form that you can fill with whatever you like to mass produce rocks. say you have 7 rocks you like. cover them with plaster to make the negative mold. then you have 7 forms to choose from. pour grout in and smear it around, voila...hollow rock