Is there a thread you could inform me of for what material would make a good fire box?
I'd use something like metal. Wood doesn't last long at all...
Now that I've been funny...the heavier the better, holding heat longer. Also depends on the grill. If it's kind of like a drum/barrel on its side, you can buy a firebox to a char-griller brand and add it. If you have a Weber or one of the square grills with the folding legs type, they're a pain to cut into.
For timing coming out, I am advocating the end of Feb. for the HavaQue cookoff in Lake Havasu, then spend a week here watching Spring Training baseball. Sure the Braves aren't here, but neither are the Yankees!