just a couple of thoughts for the guys who are going to do this I have built a couple and I know this goes against the general wisdom but I prefer to build them out of 2" and 1.5" instead of the bigger stuff one reason cause all the ones I built were temporary solutions so small cost was a large concern. One of the other reasons why is the seamed tubing fits tighter, this is somewhat of a limited benefit as most of the tightness comes from the seam in the tubing but they stay tight alot longer than you would think( at least a couple of months and still tight on one I built for a freind). You grind a place for the seam to go. I have built both the bigger and the smaller one (the larger ones being out of 2.5 seamless tubing) and I like the smaller ones that used seamed tubing for both the male and female.
