If you got a typical box hat in silver (colour optional), you could put a light plastic vanity mirror on it. 1950's art nouveaux has been recommended. It could be propped up at the back by another, smaller mirror, maybe a large, light mobile face mirror. The angle of the two main mirrors could form a rakish point. Then, in the long triangle formed at the side, a small hand mirror. Then, in the bits around the mirrors, it can be topped off with costume jewellery and other knick knacks typically found on a woman's dressing table. Ring and necklace holders, old fashioned powder containers, empty perfume bottles are all ideal. As long as it is both aesthetic and light.
The hat could be useful throughout the day of the special event as a way for people to check and fix hair and make up. It makes a statement that is topical and stylish. It also makes a social statement, because if people are getting carried away by the event (emotional and/or drunk), they can see themselves when you look at them, or even when your back is turned!