SpudFiles

I found a 1.5" Rubber Check Valve, it is the kind with the flap, if a hook was built into the valve to hold the flap shut, the unlatched allowing the flap to open, would this work as a valve? If so, that would possibly be the cheapest, reusable valve ever.

Your going to have a hard time sealing it off so it doesn't leak... it doesn't seem very plausible.

Maybe some kind of rod pushing against the flap, something with a little more force.