It's not pretty, but it really works good.  I've removed the rubber seals from the door and added some wooden laths to close the gap just a little.  You don't want a tight seal because it is important that moisture and smoke have a way to escape. The sausage must dry.  I didn't add a vent at the top. 

I've cut a circular hole in the floor of the refrigerator and mounted the hot plate from underneath so only the element is inside the smoker.  I place my wood (large pieces) in the square frying pan.  The aluminum foil pan is there to catch any grease drippings.  I use lean meat so I usually do not have any drippings.

My furnace control is mounted on the side with a temperature probe inside the smoker.  I also have a thermometer probe next to the burner control to monitor the smoker temperature without opening the door.