You need:
- a cheap letter box lock
- steel rod/shaft (D Form)
- some screws
Installation:
- Fit the Lock in the lock holder
- Fix the lock to the lock_shaft part
- Fit to D shaft into this part
- Fit this part into the gearbox.
- Fit the other D shaft into the gearbox.
- Boar a big hole for the gearbox in the back.
- Slide the Hooks and Holders onto the shaft.
- Position them on the right height,
- Screw the Holders onto the back.
- Install the Endcap so that the shaft won't fall down
- Screw in Screws in the right position, so that the hooks will catch them.
Now you have retrofitted your container.
If you need to change the gearbox use the great Getriebe Library.
https://www.thingiverse.com/thing:1604369