cold smoking... an old fridge is one way, I have made three cold smokers out of old one door fridges. The process is simple, and not very expensive. Every winter, we use our smokehouse to cure bacon and kolbasz in large batches. Downside to that is it is only cold smoke in winter, so we started to use old fridges. Basically the main thing is to find a working fridge, and build or use an exterior smoke box and attach a hose to the fridge to supply the smoke. You will also need to vent the smoke from the fridge with an exhaust pipe with an adjustable damper.
Now a few tips. My first one I had only about a six inch long pipe from the firebox to the fridge. This worked OK, but I found that the smoke was warmer on the one side of the fridge... The next unit, I ran a pipe the entire length of the bottom of the fridge, and capped off the end at the wall. Then I drilled holes in the pipe to allow the smoke to escape more evenly throughout the fridge. I made larger holes at far end, medium holes at middle, and smaller holes nearest the firebox. This worked much better. It also helped keep the smoke colder. Finally, the design that worked the best was when I extended and enlarged the pipe going from the firebox to the fridge. I used a 6" stovepipe with a damper that was 6 feet long. this way I was able to control the smoke entering the fridge better, and the smoke had a chance to cool a bit before entering the fridge. Another addition is a lower shelf where I would place 2" sheet pans filled with block ice. I rarely ever need to add the ice pans, but figured it couldn't hurt.
I am going to an auction in a few weeks, where I am hoping to pick up a few fireboxes, and a commercial size refrigerator to make a mac-daddy cold smoker. Cold smoking is great, and I wish you all the best. There are some cold smokers on the market, but i have never used or owned any. I will post pictures of my smoker if I am successful at auction, maybe even a video. Sadly, I sold all my previous set ups, a few years back so now I have only been using the smokehouse at our farm in winter....