My mention of Densified Wood was a offering to not let the OP overlook it as a option, as it is one that is an important option to learn about.
I have been doing catch up with the individual who measures all types of materials for Damping and Dissipation Properties.
There are updates to be seen where the Typical Sample Sizes of 100mm x 100mm (4" x 4") are being tested as a typical plinth size of 400mm x 350mm (16" x 14").
The latest data on the Plinth Size Material has shown a Damping Factor of 0.750
Additionally, I am to have my Pre Amp's that were designed and ready to be built, housed in a Permali Case.
The EE, has had a rethink on the design, topology and the Pre Amp's now back to a design stage. The Good News is less Casing Material will be needed if all works out.
I am keen to rehouse my Valve Phon' into a Permali Case as well to match the Pre Amp's.
I have recently seen there are Capacitor Clamp Rings being produced from P'holz where the clamped components are housed in a P'holz Casing.