A metal corner connector contains at least two connection regions which are arranged on a lateral surface of the metal corner connector. At least one connection region is configured to be mechanically stably connected via welding to a metal pipe extending along a main extension plane of the metal corner connector. The connection region contains at least one protrusion with a groove, which is configured for receiving a welding material. The connection region has an outer surface which is adjacent to the protrusion and is configured as a contact surface for an end face of the metal pipe. A method produces a device having such a metal corner connector.