Do you really want a box?
I have to comment here, as it's on my pet peeve list.
Sit in the pilot seat, strap in, then try to get something out of the back of the map box. IMPOSSIBLE.
Can't see in there, can't reach, etc.
I also like to grab something out of it when standing in front of the right wing, like when you need a screwdriver halfway thru your walkaround.
Why not make it a drawer!? Grab the handle, pull 3/4 of it out, and you can see and access what you want!...ok, you'll want to latch to to keep in from sliding into your lap on those steep climbouts.
my $.02