You can see how I made a magnetic release for one of those ponies here
viewtopic.php?f=12&t=11166.
This is the relevant photo:
- Pic_3.JPG (26.21 KiB) Viewed 2951 times
The picture is not very clear so here is a diagram which should help.
To get locked in, with the magnet is energised and the arm raised so that the weight is stuck to it, you get on, close the ankle stocks and bolt them. Then you can pull back the latch hook with one hand, put the other wrist in the stock and hold it up a bit, then put the other hand in and let the stock drop. The latch hook will then fall over the top of the stock and you are secure.
When the magnet releases the weight, the arm drops and pulls back the latch hook, as shown by the dotted lines. It is then possible to raise the upper part of the hand stock.
Do please note that, if anything goes wrong with this mechanism, you really cannot get out of this pony. You must have some sort of emergency release. As you will see from the previous post, I had a long screw with a wooden handle between my hands. If I unscrewed it, the latch hook could slide upwards to release me. It would take me a couple of minutes to unscrew it, but it would sound an alarm with the first couple of turns. This would alert Mistress K. If you are planning to use this for self bondage, please do be
very careful. Watch out for the magnetic remanence effect, which might stop the weight dropping even with the magnet not energised.
P.S. Kinbaku suggested "You can make it like:
viewtopic.php?f=12&t=11842#p84900 , but for your two hands." That might be a more reliable mechanism. If run from a battery, it must release when the battery goes flat.