Help with TSM please

I am currently looking at some gas receiver wagons and the tanks have rounded dome like ends. However so far I haven't been able to work out how to form the ends, and I would be grateful if someone could show me how?
Thanks in anticipation.

Make a tube with several sections.
Select all but two sections at one end and use the Scale button to narrow it.
Work along the sections narrowing them as you go.
Adjust each section length until you are satisfied.

When you are done, copy and paste and rotate 180degrees for the other end.

Easiest to make the tank big and resize to correct size when you are done.

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Thanks for the guidance Ian and it's very much appreciated. I shall have a go anon.