We did one similar to this though replaced the legs with some half inch by 2 ft pvc pipes and these little stoppers for them that we found at Home Depot which causes the base to sit about 2 inches up. We did that so we could then drill a lot of holes in the bottom board then placing the whole...
I've cold smoked before with a couple of cardboard boxes some flexible aluminum ducting a computer fan(to push smoke from one to the other) and a hot plate and it worked pretty damn well.
