Started this thing a year ago and just now getting time to get back on it. 24" x 24" x 40". I'll use this to cold smoke fish, cheese, and other things. Will also warm smoke sausage and bacon. All cedar wood over a 3/4" plywood box. 1.5" ceramic wool insulation on the walls and ceiling covered with sheet metal. 1500 watt heating element controlled by an Auber 1800 watt PID. Smoke will be piped in from underneath with Amazing maze or tube. First smoke this past weekend worked well, but since the insulation hadn't been installed yet, it was a pain to get the temps good in the cold weather (30s). Today I put in the ceramic wool on the walls and covered it with 1/8" aluminum diamond plate. The floor is still wood and the ceiling is still just 1/2" cedar. Both will be covered and insulated the same as the walls late this week. I did a heat test with the 1500 watt brinkmann element and was impressed. With an ambient temperature of 62 degrees, I got the interior temp up to 174 degrees in 30 minutes. I unplugged it to see how long it took to get back to ambient, or close. It's been almost an hour, and it's still at 110. Should be great once the floor and ceiling are done. Edit: need to insulate the door too. More to come later in the week if all goes well.