Yes it is nice to be able to put your projects INSIDE something isn't it? You know, to hold everything together so it doesn't flop around? Discuss the techniques here!
Check out the local hardware store. You might find something suitable that would need minor modification. If you're using friction-hinges you may not really need one.
My laptop uses a tiny flapping metal piece with a tab and magnet on the lid, magnet grabs the metal piece hooking it on the tab. Little button can push the metal piece back off the tab.