www.BoundAnna.com

This is a failry easy self bondage mechanism. It is save, cheap and easy to do.
see sketch for clearity

1. put a nut on a cord and hang it in a plastic bottle. make sure the nut can fit through the opening of the bottle easy.
2. tie a tywrap with the tying end to the rope and make a loop.
3. fill the bottle with water and freeze it.
4. once frozen place the bottle behind a fence, grate or anything that holds the bottle in place. Keep the cord end with tywrap free.
5. tie your feed and one hand as you like.
6. once everything is fixed you stick your last free hand through the tywrap loop and roll/pull with you hand untill it is fixed.
7. no escape now until the bottle releases the nut. The bigger the bottle and the deeper in the bottle the nut, the longer it will take.

Works very well.
Note that usually the tywrap will not close much further than just around your writ, but if you are planning to wrestle it, but two pensils on your wrist with tape to avoid the tywrap will close off bloodflow.

IMHO this is an accident waiting to happen - tie-wraps (cable ties here in the UK) will easily tighten and cut off blood flow, and can also damage skin to the point of cutting into it.

You really need a way of ensuring it will tighten sufficiently to restrain, but no further.

You could achieve this by threading the tie-wrap through a length of plastic tube, the tube being long enough to go around the wrist snugly. You could also damage the ratchet bed with a hot object, so the ratchet could not pass it, or could not grip on it beyond a safe point.

Much simpler to just use a small padlock linking a wrist restraint to the bottle/cord.

With LJ's added suggestions, this is a good idea. But without, I totally agree its unsafe. I would indeed go for a handcuff or similar device that you lock to the cord using a padlock.

Also, keep in mind that if you feel a bottle of water and freeze it, it may take many hours to allow escape. It will be really bad if you have to go to the toilet but simply can't, or worse.... So make sure you can break the bottle in case of emergency.

At the prices you can buy 'good enough' bondage gear from China now there's no excuse not to use purpose made lockable leather cuffs.

Ice releases should aways be tested, and allowance made for ambient temperature. I was surprised to find out how long it tool a 2l bottle to melt in average UK indoor temperature, but it was a test run so I didn't discover by being secured to the bed for fifteen hours.