Hey guys. I need help building a firebox for my fridge smoker. I just got done using it for the first time in a competition. I used a 55 Gal barrel with a flexible pipe to transfer the heat. It did really well and took home top 10 in pork and ribs but I want it to be more efficient. I plan on attaching a BBQ GURU setup to help with efficiency but have a few questions on design if you can help. Steel Guage? I hear that 1/4" thick is good but I saw that if you insulate it you can use 1/8" thick. As luck would have it I have a few sheets of Mineral Wool Board left over from my fridge so I will be using that. Design? I will be using an 18 x 18 x 30. I see a lot of boxes that have a slide out rack with a few inches underneath and I see a few that have a full basket with space underneath. Is one better than the other and if so how should it be designed. Is there a difference in how the bottom of the rack/basket the design of the bottom of the rack/basket make a difference in performance. I use lump charcoal as a base then use chunks for the rest of the cook. Damper Placements? Door Design? BBQ GURU Placement? - I see a lot that have it going straight through the door. Is this the best place or is there another location that would work best. Door Design?