Closeup of both sides and the reeded edge, with US quarter for scale. The mirror finish of the fields came out perfectly. These coins are about 8 mm across bigger than a half-dollar.
Limited edition proof run, ordering via my Etsy shop, Canterlot Mint.
UPDATE: It didn't work out in the end, but I'm still glad I did it. Coins are now selling at the reduced price of $30 each. The current run is the last one that will ever be made.