I nearly always use revolves for cylinders, no matter how simple, just because of things like this.
You can add draft to get the cylinder to taper. Then you could cut the end to a dome.
Little point to converting to sheet metal, as it will not unfold correctly.
It sounds like you want to extrude with a draft angle and add the dome and shell the part?
Of course, Revolve is even easier.
Attach your attempt here if you can't figure it out.