Check out
www.boundanna.com for ideas on self-bondage, release mechanisms, and some rather interesting predicaments.
Let us know what you select and how far you go with it.
Personally I like to use an ice release - either a key in an ice cube or some string that will release the key into your hands. If you want the bondage to last a bit longer, try freezing a key in a plastic bottle, with a string attached to your hand. Takes longer to melt than just an ice cube.