We are waiting for a mattress to be delivered, and then we'll put together something like this as a living room couch. I'm actually thinking about making two for an L-shaped sectional. See link below picture for instructions. It's very easy, simply a platform with an old door for a back. Instead of an old door, we'll use two open spaced pine boards along the back to allow for an open look. The blogger who made this couch made her own slip cover. I may purchase a fitted futon cover, or just use a fitted sheet with an Indian dhurrie over it.
It can be stained with dark tung oil(a plant resin) which is less toxic than regular stain.