Another way to consider doing this would be to fabricate a rolling
mill with tapered gap between the rolls. As you roll the ring the way
you are talking, the outer edge is going to get thinner anyway, this
would just take advantage, but might help keep the tearing down by
forcing the thinning to be equal throughout.
jk

Very interesting idea! I think I can fabricate such a device...




Take Care,
James Lerch
http://lerch.no-ip.com/atm (My telescope construction, Testing, and Coating site)

Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent.
Calvin Coolidge