alkali metalshalogensnoble gasestransition metals
Most likely the sheet metal from Home Despot is galvanized steel. Not much for interesting patinas there, either a whitish powdery finish or a rust color, depending on how much zinc is on the surface of the steel. The best metals for patinas are copper based alloys. Brass is probably the worst, with bronze being the almost best. Copper would be the ultimate best. There may be some copper sheet at HD, or other hardware stores. You might try some roofing supply outfits, sometimes copper sheet is used as flashing on finer homes or historical restorations. As far as what chemical(s) to use, the application, and preservation of the finished patina is a whole 'nuther question. Finding the metal is the first step. Good luck
