Take a look at the Conestoga grease bucket, in the "over the back fence" section, Schreck found at a collectables show. Picture the door system on this grease box, used as a pattern for a primitive tallow box. Either side opening, or end opening, would work. I love the simple use of staples to secure the pivot pins whittled on the ends of the door. A good piece of black locust, made into a door, would probably outwear the steel staples. Just a thought. You sure wouldn't have to worry about anybody getting your gun by mistake at the range.
Hungry Horse