Can you use bags of "lava" rock that is sold at the hardware store for gas grills? This rock is small enough for a background and cheap, but I'm not sure it is the same thing you buy at the petstore. Any help?
i'm using some vinyl gutter material and cutting holes in it, then siliconing the rocks to the glue. I saw it somewhere on the web. I will try to find the link and post it. I am doing it a little diffirent than that guy did, I will be making vertical and horizontal caves and the vertical ones will hide all the pipes and cables.