I used great stuff for my back ground in my latest enclosure and I didn't think it was that difficult to work with. Just take your time, use gloves, do it in thin layers and build it up over several days so it has time to dry. It is very easy to carve with a knife or a razor blade into anything you want. You can embed rocks or sticks into it. Again just take your time and if you don't like what you've done its not hard to trim it down and start over. Then smear silicone over it and pack on coco fibre or some other substate that you like the look of. Then use a small vaccum and suck off the excess.