The metallic line of Ericofons was done by the Nichco phone company in Ohio in the late 70's. The Ericofon line was getting tired and there were a lot of aging, discolored   phones gathering in the storage rooms. To spice up the line and recycle shells, they came out with metallic paint Ericofons. I have 11 in my collection, I'm not sure exactly how many colors they did.
Im not sure if any other company was involved in painting the metallic colors. I have only seen the Nichco label on painted metallics.