The O ring idea fascinates me. it should be easy to figure out the problem is yo need somethe between the ring and the tube. Also if you could get them to cut short sections of reasonably large rings that can be sealed off you can make resonance dampers for speakers . I think resonance is good, as long as it does yield a distorted sound. I tell yo what we can find a smelter oif led to fill them have plastic caps melted onto the ends add a layer of iso damp and cork then prl kitchen flooring and finally a cup of ball bearings and charge 300% more than the cost.
