Looking for plans or at least drawings to build a flip-up or pull-out stand for a laptop. Couch faces back of dinette. Hope to build stand or shelf on back of dinette so it can extend out slightly over couch but will lower or retract out of the way against the dinette when not in use. Prefer to avoid a leg support. Have seen shelves between the barrel chairs in RV's that lift up and then flip forward. I believe there was some kind of internal bar that supported this shelf. I have not been able to find these for sale anywhere - and even if I could, the size might not work for what I have in mind. My husband wants to go with knife hinges but I'm afraid they'll interfere with knee room. Any ideas?