Here’s an interesting hack that will allow you to build d DIY keypad door entry system. The highlight of this system is that you can hack a normal keylock with an RC servo, brilliant!
I believe that kids (and not only kids) that have their hands on electronics, wanted at least once in their lives to make an electronic keylock system for their house or room. When i was a kid, i had bought a Smart Kit Keycode lock system, and i had adapted it on the external door of my house. But this door had already the automatic-release mechanism. I only had to find which wires actuate this mechanism and hook the relay of the kit in parallel to this.
I actually was fixing a door lock the other day but this would be much better/high tech method, I might consider it for the near future.