Here is my dilemma. I have this grill that is 1/4 X 24 X 48 pipe, cut in half so I'm not sure what the volume is. This makes Feldon's calculator a bit tricky to use. It has no lid so I need to make one and that is my first question. What dimension does the lid need to be? It will obviously be a rectangle, and I was thinking 12"H X 2'W X 4'L. How big should the fire box be? Thinking about 20" X 20" X 18". What size should the opening to the CC be? Considered the football shape at 8"H X 20" across. How far up should the RF plate be, and how big of an opening should be at the opposite end of the plate? Here are a couple of pics if this helps.