I'm with PJ! Great idea.
If you're going as the Wicked Witch of the West from the MGM movie, she wore black hose and black shoes, not unlike the Ruby Slippers in their form. Probably the same exact 1930s pump used, before the red sequins were sewn on.
Hers were flat black (no shiny leather) with no adornments on them. Still the shape is very much like "her sister's" shoes. You can actually see them fairly well for a moment (particularly on the new Blu-ray release). Right after the Ruby Slippers disappear and the feet curl up under the house, the next shot is of the Witch turning around and walking back toward Dorothy and Glinda. That's when you can see her black (semi-transparent) hose and the shoes. You can also see them in the Witch's Castle, when she catches up with Dorothy and her friends, just before she melts. Her entrance shot is where the shoes are visible.
(Yeah, I know WAY too much about this movie.)
I also know someone here in L.A. who owns one of her hats and a pair of high-buttoned black shoes (ala Mary Poppins style) that were tested for the movie, but never used. They've got "Margaret Hamilton" and "Wicked Witch" sewn into the label just the same.
"Jaws is the Citizen Kane of movies."
blocked: logan2, Diamonds3, Hamilton22