Hello from Sedalia, MO. My great grandparents had a small smokehouse. It was about 14 x 14 ft with a pointed roof (12 ft high on top) , and 8 ft walls. It was made out of 2x6 rough cut oak framing and pine sheathing covered with felt and pine siding. I remember the wood burning stove and the chimney (stovepipe). They had some shelves on two sides about waist high and some assorted wooden hanging racks for the hams, sides, shoulders of the many hogs they butchered each year. Then the big beams for the cattle to hang from. They seemed to have butchered more hogs back then and that is mainly what they smoked. The cattle were butchered and cut up right away (always in cold weather) and the beef went to the locker before they had home freezers. They still had workable ice chests (cabinets made of cedar or redwood) when I was very young. They had a concrete floor and sill on the building to help keep out varmints. And a very small window. Hope this helps. I don't think making one out of galvanized steel is a good idea; but maybe enamel steel or exterior plywood?