Another possibility is to use a thick wide belt with two attached magnets (behind the back, ~10cm from each other) and two batteries. The wrist cuffs will have only the metal disks/cups.
In arcade games, pinballs, cranes, we use solanoids. They have two parts. The coil and the plunger. The plunger can have a steel ring on it, and the coil, located in a steel housing, can also have a ring.
However, the wires are still a problem.
The coil can be engergised and as soon as you place the plunger in the coil, it locks untill the battery weakens or the wires are cut.
The wires can fit in a flexible steel tube to the battery.
Thinking about this, the solanoid and plunger looks a lot like an ice lock.
Battery holder?
Take your 9 volt battery, and Ducktape it to the solanoid.
That should keep it in place.
I think I have a solanoid around here somewhere.
True, but once the battery connector is connected to the coil, the coil is now on. And, once you slide the plunger into the coil, it will lock in and stay locked till the battery goes dead. Then the plunger will be free and so will you.
Oh, almost forgot, not all solanoids are round. Some have a square frame that a battery clip can be bolted on.
That would solved the Ducktape.
True. I was thinking about something like the ice lock.
Any ideas where to get suitable round plates?
