These are the beds we built from rock on our property. When we moved here the woods came right up to the back of the house and to the driveway. We had to clear it for a backyard and the barn and horses' paddock. Plus the fact that NY is practically all rock. So that is what these beds are made from and it didn't cost any money just manual labor. They are great for gardening because they stay warm from the day time sun through the night.