Converting an old refrigerator into a smoker is relatively easy if you’ve got all the racks. Such a smoker is also convenient to use. Many people put a hot plate in the bottom of the refrigerator and cut a vent hole in the top. This rig may or may not be satisfactory for cold-smoking, depending on how much heat it generates. It’s best to check out the unit by leaving a thermometer on one of the shelves, or drilling a hole and installing a more or less permanent thermometer that can be read from the outside.