Nicely designed tool - thanks for posting that.Back when I used to do plumbing we had a tool to build flanged tailpieces (the part that goes immediately below the sink drain to the trap). It consisted of a sleeve that was split so it could go around the brass tubing and be clamped in a vise with enough sticking above to form the flange. Then there was a cylindrical piece that got put into the top of the tubing with a hinged part with knob that you crank around a few times and presto, you had a flanged tailpiece.
A guy could build a similar rig to form the flare on a downpipe or whatever. This is similar to the one we used. Speed Type Tailpiece Flanging Tool - Specialty Tools for the Serious Plumber
I agree, this tool won't do the flair. I looked all over the lisle website and found nothing.Those just expand the pipe so you can do a lap joint with another section of exhaust.
I understand that Kimber1911 is wanting to flare the end at a 45 degree angle. That could also be done with a support ring around the outside near the end and then use a hammer to bend the flange out. That's a bit *******, and might make the flare a little uneven, but with care it would work.