Appearance and Mechanics Edit
The marionettes appear just as regular marionettes might. When the Crooked Man places his enchanted ring on a girl's finger, the girl immediately turns into a marionette if she is not the reincarnation of Cheryl. We are told that he has done this to countless young women since the death of Cheryl. He stores some (or all) of the marionettes in his Crooked House, in a room called Marionette Hall.
We don't know anything for certain about the marionettes or how they came to be the result of the Crooked Man's failed attempts at finding Cheryl. The marionettes bear a striking resemblance to the highly detailed work of Geppetto, and evidence of Geppetto's knowledge of the Crooked Man can be found in a secret chamber in The Final Cinderella. How exactly he might be involved is unknown.