I got sick of waiting for slabs to dry out in my basement so I built a really simple kiln. The floor is green treated lumber 16" on center using a 3/4" subfloor plywood. The sides and the top are framed using 2x4s ripped in half as well as 1" thick foam board. Sides and back are just screwed together since I am lazy. Overall, it is 4 feet by 8 feet at the base and 4 feet tall since that is really easy to make with standard plywood and foam boards. Most of my wood is for woodworking and is under 8', but you can easily expand this to a 12' or even 16' length. Inside there is a household dehumidifier and a small fan. Not sure how well this will work, but figure the it was worth a shot. This breaks down into the base, sides and top for easy storage if I don't need to use it for a while.