well, I am doing my first car model, I am doing a mini, Mr Bean style, for my friend for christmas.
As you can see on the door, he uses a deadbolt to lock the door, (hides the key in the trunk that unlocks a key in the engine, which unlocks a key under the wheel, which unlocks the lock, or something like that. Then the key is tossed into the window, heh)
I have started working on it, not sure how to go about doing it detailed though.
so far I just have the base for it.
I love my luck. I’m thinking, how am I going to make the lock itself? I go to plug in my dremel, to try and make the little thiny thin parts of the hanging lock, and I see this! 
Im so glad I disected that mouse.
I still need to do the bolt and all of that, not quite sure how, but Ill figue something out, may use a wire for it.
Ok, glued one strip of syrene on the other, one slightly smaller on all sides.
When it dried I used my flat file to file a grove, as you can see on the referance pic. I then used my dremel to square it up and put the grove on the sides as well.
Then using a diffrent head I drilled a hole in the side (which is really the bottom, but how it sits its the side)
I then used gorilla glue (only super glue I have, it serves it’s purpose) to attach the lock to the deadbolt.
and Voila! My first real scratch build of something, tell me, how is it?
Nice Job!