I don&#x27;t know how useful this will be. I think being made from crushed gneiss in a jammed configuration, it should be fairly strong in pure compression. Bending stress would probably cause failure quite rapidly, and I think it would steadily weaken with vibrations of sufficient amplitude, especially if it wasn&#x27;t loaded.<p>That said, I really don&#x27;t care just how useful or practical this is because it&#x27;s already so damn cool. That trick with the string is very clever and I would love to see the mathematical model they use for planning its path.