We just have a door handle inside of our balcony door with a magnetic lock, so the problem was that the wind opens the door every time when we were outside. So I decided to make a mechanical door lock for the outside. Its the 3rd version, because without a metal screw the material was not as strong to withstand the wind pressure (or our toddlers pressure).

You need a M8 x 20 (or M8 x 15) countersunk screw as the strong part of it.

I recommand PETG for the outside. Don't use PLA!!!