Cold Smoking is the process of smoking an item at a temperature below 100F degrees.
This technique is used to cure meats or impart smoke flavor into foods. Cold smoking is typically used for things like cheese, fish, sausage, or bacon but can be creatively used on just about anything.
To make a cold smoker all that is required is the smoke source and a container. The container is usually a grill or smoker but I have seen people use a cardboard box. There are many options for a smoke source and the key is to keep the temperature low in the container. One option is a metal can filled with sawdust or wood chips with a soldering iron inserted in the bottom. You can also put a couple briquettes in a can with wood chunks or chips.
If temperatures in the cold smoker are a little high you can lower them by putting a pan of ice in the smoker.