So I am considering building my own UDS. I am quite handy with tools and think it would work out. With that said, the cost would be about the same as the Lowes Master Forge charcoal smoker, about $60. I do think that the quality and size difference would be greater with the UDS though. Any thoughts? Also, what are the 4 fitted pipes at the bottom for? One has a valve. Would those be for air intake and the valve being for cleaning?