nostr:npub1canhdnyarz4thu7zgzz3hv3nw0al770etgjjawqukxuw82ceuz6qmq0fm9 messier if it breaks but could work too 🙂 dampening would be better than plaster i think… if the sand is fine enough and does not vibrate itself against the plastic shell. I could imagine that happening if the space between walls is not big enough to filter all resonances