This is a case for rectangular electronic keys for an intercom.
It consists of two halves, one of which is glued into the other.
key_thick.stl - a narrow box for the key entirely together with the coating.
key_thing.stl - wide uncoated key box
It is best to use b7000 glue, but cyanoacrylate or plastic glue is also suitable.
Key sizes: 50x24