You can make textured walls, benches and other objects that look just like stone. This video and the article below show you the basics. I prefer the beauty of natural stone, but this is an option worth considering for special situations. Here’s one example. You could plaster your walls to simulate the color and texture of stone using earthen plaster. Then mist it with MICP to create rock hard walls. You could also plaster your walls with lime or geopolymer plaster and add stone texture and colors.
More info: How to Build Fake Rocks