Anti-vibration balls for hifi racks

@incorrigable your idea may work the best for me!

The Star Sound people used to sell something they called Micro Bearing Conductive Steel.  Star Sound used it to damp their Sistrum Stands and their cables, and they sold it in plastic jugs for damping audio racks. I used it in DIY cables and still have a small jug of it.  It is no longer sold but it probably the same as, or very similar to, the steel shot for blasting discussed by @jsd52756. Maybe like this (link).

Lead isn't a hazard issue just pour melted wax into cavity to seal in the lead or whatever ...

FWIW, the Star Sound people (Sistrum stands/racks and Audiopoint brass footers) are still around under the name Live Vibe Audio, LLC in Delaware, USA (link).  I did not see the steel micro bearing material listed for sale in their products but they discuss using it as fill for the legs of their Rhythm Platforms (link).

The presumed benefit of using their micro bearing material is discussed in this product description (link) under the heading “Setup”.