Today is my birthday, I get to be a princess for a day (although sadly the day is coming to an end). I made a tiara out of black 18 gauge florist's wire and aluminum roses (just search "aluminum roses" on eBay, they are really cheap). Kate who?
I copied the violin purse made by Lace Story. Cut out two pieces of cardboard and cover with white pleather, glue one piece to each side of a semi circle shaped purse, add accessories and handles.
A great material for cocktail hat base or fascinator base is plastic lids for cans (Pringle can lid, small coffee can lid, etc). Simply cover the plastic lid with anything (fabric, leather, sequins, etc) and it's ready to decorate. I bought the cherry from eBay at 25 pieces for $3, they are very realistic looking.
I made a pair of shoulder piece from black feather pads. They are very easy to find nowadays (or buy two headbands with feather pads and take off the headband part). I used regular brooch pinbacks to secure the feathers onto clothing. The chain can be detached so they can be worn individually.