Let start by saying I think using a file cabinet as a smoker is a great idea.I apologize in advance if what I am about to suggest has been posted previously. I have seen other posts about file cabinet smoker's where there is some concern over heat retention. So here is my suggestion for a file cabinet smoker with the heat retention of a ceramic smoker....use a fire cabinet. A fire cabinet is a file cabinet lined with concrete. The cabinets are not cheap, even used they are bout $800. Just a thought......