I want to find a cheap valve that will let me take a breath in from one place then exhale through a tube going out so that i can attach an airbag to the breathing end and make a little diving lung.
What your looking for is a check valve. Home Depot Be careful, very careful!
Creating a proper valve system for the creation of a diving lung is not as simple as you think. You require carefully balanced directional pressure regulation valves. A simple one-way valve (AKA check valve) would remain open and release all the air from the airbag as soon as the airbag was subjected to water pressure.
