I have 8 metal shield keychains from Game of Thrones.
They are 2" in diamter, and are perfect for MOTUC. The keychain loop can easily be clipped off and filed down and the fit amazingly well. Another cool thing is the wolf insignia is raised, so it could be filed off as well if you wanted it to be plain.
$10 shipped (in US)
"The surest sign that intelligent life exists elsewhere in the universe, is that none of it has tried to contact us." -B.W.