Here’s an interesting Web site dedicated to escapology. Two pages of the online catalogue (here and here) offer a variety of handcuffs for sale to the enterprising escape artist. Two of these cuffs are actually called "seance handcuffs" and are similar to those used by fake mediums in Houdini’s day.
Also note that gimmicked flex-cuffs are available as bulk orders. The flex-cuffs can be opened and reused. Quoth the site:
YOU can use these SPECIALLY-GAFFED Flex-Cufs again and again, because you can escape from them WITHOUT CUTTING THEM! Here’s the presentation: You cross your wrists in front of your body, and your assistant locks one of these Flex-Cufs on your wrists VERY TIGHTLY. A SPECTATOR THEN PULLS ON THE CUFFS VERY HARD, AND SATISFIES HIMSELF THAT THEY ARE INDEED SECURED. (This part is VERY convincing). However, you immediately escape without the use of cutters, or tools of any kind, and show the cuffs to be still in one piece (no switching of cuffs).
Cool. But who could possibly have a use for such a thing?