Asslam u alailkum This is first time I am posting my project here . i am going to tell you about making a very cheap door lock

Step 1: Things You Need

All the things you need are
Some wires
An old useless servo motor or any motor with mounted gears
an old rc car
Glue
Screw driver

Step 2: Making

First of all you have to open the servo motor using a screw driver
You will see that two wires from servo rc are connected with a motor
Disconnect these wires from ic of servo motor
Now open the rc car and get rc receiver disconnected from the rest of car
Usually even cheapest rc car receiver can run two motors but we have to run only one motor
Connect the two wires of motor(that is inside the servo motor) with motor terminals of rc receiver
Now connect the servo motor rotating head with door lock as shown in the picture or in any other way so that lock get locked and unlock with servo motor up and down motion.
Connect the rc transmitter with battery and paste it on the back of door with glue
That's all you have done Now you can use your rc car remote to lock and unlock your door