This is a scan of the plaque on the cabin door of my recent Alaska cruise. Doors were steel, and these plaques have magnets on the reverse.

Not quite an ice machine, but kind of unusual casinobilia.

It had practical value, as ships corridors all look the same and the directional signs were not clear that odd and even cabin numbers were on opposite sides of the ship. Nice to check for your name on the door before trying the lock [g].