Behold the Cold Smoker 5000XR (the “XR” stands for extended release — I was working on a patent case at the time involving an extended release formulation):
The food-hanging box is made of redwood lumber. The TTR (thermal transfer reservoir) is made of Trex plastic lumber — I wanted to simulate a trench dug in the ground where I could “bury” the duct in the cool earth. So this is made to be filled with soil and ice cubes, with a wire mesh in the bottom to allow water to drip through.
This is the only brick masonry I’ve done in my life, and it is probably my last. I will stick to patent law. But it works, and has held up for many years. The only problem was that I initially covered it with a thin piece of tile. Once the wood chips in the TA caught on fire, and it got pretty hot in there, and the tile cracked and the flames leapt up. So now I use a landscaper paver, about an inch or two thick, as a lid — that had held up beautifully. The ducting is the heavier gauge laundry ducting, also available at Home Depot. I futzed around with various elbow joints to allow the duct to dip down and be “buried” in the TTR, then reemerge and bend into the smokebox.
I use a computer box fan to draw the smoke through the duct, and various wood dowels to hang the food. I’ve since built a shelf out of a wood frame and quarter-inch wire mesh, for smoking cheese and nuts, and other things that are cumbersome to string up.