All the work I've been doing on panels, their resonances and damping, can be applied to panels used as supports for turntables, or any electronic hifi component (and, indeed, loudspeaker panels). A support has the same function as a turntable plinth, that is, to damp unwanted vibrations, whether they originate in the item on the support, or from the air or floor or wall or wherever the support is.
The mathematical modeling has suggested that single material construction is not ideal, unless one invests in expensive panels of Panzerholz or casts one's own resin, and even in the latter case, strength must be an issue. This seems to be an area where composite sandwich construction of cheaper materials should work very well, with a core of mdf or chipboard and skins of aluminium or acrylic.
I have to do a lot of work in this area to determine which is the best way to go, but I have found a couple of composite materials which look promising. The first is a panel made from two layers of glass with a polymer inner core. This gave a damping factor of about 0.39, very good. However, I have been informed it costs £1000 per square meter. Another composite I found promising is a panel comprising a fibre/resin inner core, sandwiched between expanded polystyrene sheets, encased by a thermosetting plastic. Again, there's further work to do before a firm recommendation can be given.
Active supports and damping
Most damping is passive, relying on the natural damping ability of material damping factors to reduce the amplitude of the vibrations exponentially, (or not!). There is another form of damping, which is active damping, where a system is used to apply electronically derived damping. Such systems can be simple, using piezoelectric principles, or more complicated ones; the one I use under my phono stage preamplifier is a kitchen scales product, made by Salter.
Salter 1004 SSDR stainless steel square © Amazon
I can't say I have carried out serious listening with my Cambridge Audio P640 perched on top of the scales, but I use it this way all the time, and I'm getting a sound (from the whole system) that I like. I think there is some mileage in active damping techniques. By the way, the damping factor measurement was 0.226 @ 364Hz for the scales, whatever that means in this context.