To change appearance at will (Claimed)
Metamorph Medals are supposed to help the wearer metamorphose. Actually scam objects; they actually make the wearer turn orange, or in worst cases, cause him or her to break out in tentacle-like warts.
In 1996, when the whole Wizarding world were aware of the return of Lord Voldemort, some people decided to take advantage of their terror by tricking them to believing that the objects they sell actually work so as to scam them out of their money (each medal cost ten Galleons).
When the Office for the Detection and Confiscation of Counterfeit Defensive Spells and Protective Objects was created, the head of the depatrment, Arthur Weasley confiscated a bunch of these Metamorph Medals.