I didn't use an old fridge as they are just too hard to find and with the external heat source and such. I did build one out of 5/8" maple plywood that is: 3'h X 2"w X 17"d. I use standard oven racks that I scrounged and an 1,100 watt hot plate along with a 8" cast iron skillet for a chip pan. Also I used some 1" sq oak that was given too me for the rack runners. Just make sure you cut everything real tight so you don't have toooooooo much ventilation. A carpenter I am not! But I fixed my screw ups and it works great. Good luck and tight lines.