Traditionally tailcoats are worn, but nowadays suits are also worn. Women often wear dresses. I already have been told it can not be too much. Now I am looking for something festive/gala/official/presentable to make.
Last year I bought this satin woll suiting that was called tuxedo-satin by the shop. It has a dull side with shiny stripes and a shiny side with dull stripes. The stripes are small (7 per inch). I have more than 5 meters, that would be enough to make a three-pieces suit with an extra skirt.
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I came across this picture of a long bodice-dress in a fashion magazine. A long black dress would be very festive and appropriate. The skirt part should not be too slim (pear-body shape) and not too wide (because the fabric is soft but heavy, and striped; and because of the occasion).
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burda magazine 12/2008 "Bambi awards" also has many patterns that go into the right direction. I think I should have sleeves or a blouse or a jacket. Not sure yet if I should make a one-piece or two-pieces dress.