You can anneal your strip of 1/16" steel by heating to red heat, hold it there for 60secs or so and then allow to cool slowly
If you are going to try it in brass then use one of the softer brasses as hard brass can crack if you are not careful.
Best way to bend it to machine up a bit of hardwood to 1.375" thick and put a small radius on the corners where the metal is to bend. Clamp metal to one side and bend to form the bottom then add another clamp so it does not move while you bend the metal up the other side. Start with a strip of metal that is plenty long enough then you can trim back each end to side once bent. Do the hole after bending.
Same when you come to do the curved part that fits the smokebox, bend that up over length and then trim back once soldered to the "U" shape. Finally make the two end plates by marking off from the soldered up perch bracket that way if your sizes are a little off the plates will still fit.
Edited By JasonB on 23/12/2017 16:47:12