The World's Simplest Latch

A simple latch to keep a small door, drawer, etc. closed.

My chinchillas kept breaking out of their refurbished closet enclosure because the door magnets were too weak and they are really curious. Starting from the wrong end of the equation (my default setting), I started by downloading and printing a huge elaborate bolt latch system. After over 6 hours of printing (for just one of them), I noticed they wouldn't even fit due to some design features on the door panels.

Starting from the o