Flaring the conical end of a metal ring

[TomG]

I was going to suggest a roller as well, but it would take something a little special. I assume you are starting with a washer shaped piece and forming it into a cylinder, so it would take three rollers with the center one able to tip a bit to put more pressure on the inside edge of the washer than the outside, to raise the it into the cylinder shape. You have raised my curiosity, so I may be forced to try it out.

Tom