TubeNet

The video is pretty abbreviated. The things I would have liked to have seen is getting the taper right and if they used a tapered mandrel to get the final size. Also... surely they annealed the material more than just once while it was in the flat.

There is always the way I learned. Take a straight tube a bit larger diameter than the large end and draw it down using only a draw bar, a micrometer (or callipers) , something to measure the length (a piece of string) , a keen eye, and maybe some intuition That worked for the old masters like Carl Geyer.

Once upon a time we didn't have dent machines and rollers and a lot of other nice toys current techs have!