vintage enamelware, large heavy enamel medical lab / industrial tool tray

Very large heavy vintage enameled steel tray made for commercial use... a photo lab developing tray, or a tray for labratory or medical equipment? It's 21" x 13" overall, about 2 1/2" deep. Condition is very clean and nice, though the enamel has a few worn spots and a bit of scratching.