Aluminum Smokers
The easiest way to make a smoker is to convert a 30-gallon aluminum trash can. Drill four holes in the bottom of the can and in the lid to promote air flow, install four stainless steel cross rods to support two grates purchased at a barbecue supply store and install a water pan on the bottom. You can also fashion your smoker from sheets of aluminum if you have a welding torch and the skills to fuse aluminum without destroying it.
Stainless Steel Construction
Stainless steel smokers are more substantial but also considerably heavier, which may be a handicap if you plan on transporting your smoker to various locations. Use a heavy gauge steel, just under 1/8 in. thick, to best insulate the smoker during extended smoking of large cuts of meat. Support the body of the smoker with 1-in. square steel tubing and equip it with store-bought grates and a water pan. If you have access to stainless steel food-grade barrels that have never been used to store or transport chemicals or other questionable substances, they can be converted to smokers using the same procedures as the aluminum trash can conversion.
Other Metal Options
Salvaged metal is acceptable for the body and supports in a homemade smoker as long as it is clean, free of rust and unpainted. You can use discarded conduit, water pipes or rebar to support grill pans. Metal fabrication shops and construction companies frequently sell odd-sized leftover pieces of aluminum and stainless steel at reduced prices that can be used for the body of the smoker but be sure to check the remnants for holes and gashes that would render them useless to contain the smoke needed to impart foods with tenderness and flavor.
Considerations
If you are building your smoker to save money, take into account the auxiliary costs of welding materials as well as the time you will invest in the project. Another consideration is the warranties included with commercially made smokers that guarantee their performance and replacement of faulty parts, assurances unavailable for do-it-yourself home-built smokers.