I've got a Sea & Sea Pro Ex w/strobe and would like to make it a little more bouyant, I don't like the way it just sinks if I have to let go of it when I need both hands to do something else (I have it tethered to my bc with a quick release coil lanyard). If I'm near or on the bottom, (which I usually am when taking pics), there's the danger sand or rocks or what ever may scratch the lens. Can someone recommend a way to make it at least nuetral or slightly positive buoyant (preferable) with easy to find materials?