Small metal cabinet to embed in the wall?

[slaskman]

We are going to build two gate posts and have the idea of a small built-in box with a padlock to be able to leave keys for craftsmen, etc. Does something like that exist ready-made, or do you have to weld it yourself?

 

[major_tom]

should be possible to install one of these in some way?
https://www.jula.se/catalog/bygg-och-farg/beslag/hanglas/nyckelhanglas/nyckelskap-343583/