I got this book that's about making concrete Garden art...and I saw something that others might be interested in. You can imbed steel nails, nuts, washers, bolts,etc. in your hypertufa objects and it will RUST! You can create designs and patterns like a mosaic. I was going to try this and then I dumbly realized that my nails were galvanized so I need to go get some others to use. They should be cheaper anyway.