Jeff; I do this all of the time on my large spinning lathe. It can easily be done on a metal lathe with a chuck and spindle hole large enough for your tubing. The best way to grip the tubing is with a collet. For a large diameter tubing I'd machine my own collet type holder to place in the 3 jaw metal lathe chuck. You can make this out of heavy walled steel tubing with a slit in one side.
It can be done using nothing more than a good sized planishing spinning tool. For quantities, I would most likely use a scissor action roller tool with the correct radius roller. This is less tiring. To just turn in the end you do not need a mandrel inside the tubing - just lube it and fold it over. The end does need to be cut perfectly square or trimmed before the spinning begins. Take your time with the process and go at the speed the metal dictates or you will crimp it. I usually do it at 1200 to 1700 rpm on the lathe. If you make your own simple roller tool (as is used in Japan), be certain to keep the roller bearings lubed. Jim