Fill with dry wood sticks, get it hot to breathing fire, red/white coals in the bottom, then set it upright on a fireproof surface and leave it to self chimney for awhile. Or TORCH it. After it cools down, use a hive tool to wack and chip and scrape off what is left. If your goal is to have a nice shiny polished smoker at the end of it ... you might want to reconsider where best to otherwise be focusing your time.