Cob is the most creative building material that I know of. Once you have the mass of the wall for structural strenght, then there are all kinds of ways to make little alcoves, shelves, arches...and...ART! You can build up the wall with cob and then add layers of earthen plaster ...and sculpt! In these walls we put some clear onyx stone to let the sun shine though. At night from the outside the stone lights up and looks like a sun or moon on the house...and in the day, the sunlight does the same as you see it lighting up from inside. We used Tequila bottles and blue wine bottles for more creative ways to bring light through the wall. We also added a gorgeous hunk of marble (just build it into the wall) that I love because the detail in it looks like a forest.