I'm fascinated by Smok'n Steve's little Twiggy and Lumpy smokers he has shared with us here, and have decided to build one myself. I happened to score a couple of free SCUBA tanks that are 24" long, rather than the 18" SCBA tanks that Steve used. This got me wondering about the proportion of the firebox to the cooking chamber. On the Twiggy's, Steve uses a 6" firebox on an 18" cooking chamber, or 1/3 the size. On Lumpy, the firebox is much bigger in relation to the cooking chamber, yet the proportions look right there too. Does anyone think there is a formula to this? I understand most any sizes could be made to work, but one thing that stands out in an appealing smoker design is the proportions. Thoughts, anyone?