Use drawer slides; mount the drawer on the wall; attach the shell to the slides, so it pulls out. Shifty Desk / Hallway Stand by Daniel Schofield This is such a great storage idea! It can be a shelf and a drawer.
Great way to save money and utilize your space! Turn your office into a guest room. (While this seems amazing, I can't help but wonder: Who would feel safe on a DIY Murphy Bed? AND Would I want that person staying at my house!