document updated 11 years ago, on Aug 29, 2012
The idea here is to construct an almost fully-enclosed cavity for the pouch. At one end of the pouch, there would be a "lid". The whole thing looks somewhat like a pitcher plant.
The "lid" would be hinged somewhat, and would support the weight of the release-string. When the string is released, it allows the lid to open.
A good picture of this is here (called the "cluster sling")