[BigBellyBBQ]

dont waste your time buying strips from Home Depot....there are several sheet metal shops in your area, they have scraps or drops that you can pick up for cheap..they can shear even what you need...belly up to a local shop, they will become friends for food! and you will need angle iron, strips, grates all shorts of raw material..you will be a kid in the candy store..round tubing..square tubing...some good stuff...even go to scrap yard..stainless exhaust for 2 bucks pound! endless opertunities for cut offs...

a Backwoods design has the heat / smoke moving on the outside perimeter, not just vertical convection, it travels on the outside, as this is a double wall construction, approx 1" space between the outside and inner cooking chamber, then transfers at the top into the cooking chamber and then exits through the bottom of the cookiing chamber to the exhaust chimeny..a boiler plate seals the fore pit from the inner cooking chamber..
if you decide on a upright box cooker and just using a fire chamber open to the food, like a big wsm, you will find all wood cooking will have very uneven temps inside your food chamber, a great minimal heat loss to the outside, however due to the size of cooking chamber and radient heat loss, you will need btu's to maintain temp which might cause food to be dark so install baffle plates and direct the smoke to the outside walls, to eliminate direct heat / smoke on your food, this will give some time for the deposits/ residule to attach to the walls and not the food..
also dont waste your time with rust removal, clean with good soap and water first///once complete a couple hot fires then coated with veg oil will do the trick.
use a cup wire brush though on your seams where you are attaching braces or supports and if using gaskets coat your mating surfaces with food grease or pam..
you are welcome to stop by the shop to see a backwoods or others if you need ideas..
I have built many many smokers / cookers/ grills and it is a fun trip every tme..so much to do and then that first cook is very rewarding!!