We prepared 3D printable elements available here on github, so if you want to print them and attach on your door lock. We don't want you to destroy your doors, so we made it easy to attach with some screws or tape.

First of all, solder some wires to the RGB LED. It will be the indicator, so we use only red and green color. Then insert LED to the larger gear.

We attach the PMMA plate with tape under a door lock for CORE2. There are 4 screws and 4 distance nuts. Then insert the larger gear on a knob, and tighten it with screws.

Tighten CORE2 with 4xM3 screws.

Next, assembly a servo with the smaller gear and the base. We tightened servo with 4xM3 screws. Then attach it above a door locker, so it will be able to move correctly. We used tape to attach the base with the servo to a door above the lock. Bear in mind, that the program will be starting at the open position, so unlock the door and make sure, that the servo is in a correct position before assembling gears togheter. The best is, to do it after programming, so the servo will be in the desired position.