There's a compartment behind the dinette seat that offers some additional storage. It has a nice door with a 1" hole. Others have mounted a simple cabinet lock there to provide a potential low level of security. It seemed like a good idea so I decided to work on this. The lock I could find (and it seems most of these) use a 3/4" shank. That makes them a bit small for the hole in the cabinet. The lock comes with a bezel you can use to "fill" in the gap, but I thought it looked and worked horrible. I wanted a more solid approach.
I ended up milling a part out of some aluminum to hold the lock and mount it securely to the door. It also fits snuggly so the whole thing has a more solid feel.
And here it is installed. I added a plastic tab so you can easily pull it open if you don't have the keys and it's unlocked.