Jacques-
Perhaps you could look into the Orotone process. It is printed on gold-
(leaf?)- backed glass, not so unlike the black-backed ambrotype as I
understand it.
Jack Fulton (on this list) recently informed me that there is a woman in
the Bay area that is (was?) working with this process today, and there are
apparently others as well, if you are interested.
Good luck-
Jon Bailey