Suppose you wanted to detect gravitational waves from a lab source (I know, any reasonable man-made source will be several orders of magnitude below detection technology, but humor me for a second). The first thing you will want to make sure is that any mechanical signal from the source gets attenuated at the detector below the expected level of the gravitational wave. Assume the detector itself is sensitive enough to detect whatever gravitational signal is received at its end
So I've seen that some experiments reduce noise by placing equipment into granular support that efficiently disperses mechanical energy.
But also it seems (to me) that a single material would behave worse than multiple layers of different materials that make multiple scatterings of any leftover waves at each interface.
What is the optimal mechanical insulator infrastructure required for a gravitational experiment on the range of frequencies where a mechanical source can typically spin? (i.e up to a few kHz)