I have been thinking up a design for an isolation table recently too.
My conclusions:
A mechanical suspension system with the component shelves being suspended by an elastic material is likely to be the most successful, though I have no evidence for this. The main problems with this are that I can't think of a way to build a rack that would not look like a dog's breakfast, also the lifspan of the elastic would worry me.
Therefore a more traditional route should be looked at. It is my view that an equipement rack should have (1) great mass (2) isolation features (spikes and/or gel/air seperators).
I came across Tony Gees design
http://www.humblehomemadehifi.com/Flexy_Ref.html which has some of the characteristics that I was looking for, but I feel that significant improvements can be made relatively simply. The advantage of Tony's design primarily lies in its great mass and rigidity.
The whole table/rack can be isolated from the floor by making the legs into spikes, or using the round headed nuts if the table was to be placed upon a hard surface.
Rather than use Hawpathon (which is expensive and hard to get hold of) in the shelf sandwiches, I would use steel shot, which is readily available from shot blasting companies, I would also place a copper mesh sheet, or similar in the sandwich and earth each shelf. The steel shot and the copper will conduct RFI nicely away. Whether this is an issue or not is unclear, but it is a simple solution and cannot hurt.
So we have mass that prevents movement, spikes that prevent vibration, grounding that prevents RFI.
The only isloation technique that we have not used (except the suspension method which I had ruled out) is the use of gel feet or an inflated air tube cushion. I propose to seperate my equipment from the shelves by placing them on an MDF plinth supported by Sorbothane feet, or a partially inflated bicycle inner tube. My equpiment is quite heavy 10-20kg each, so I would need the 2" Sorbotahne feet which are not cheap.
My idea is based upon the mixing of a multitude of techniques. I have no idea which are the best, and if indeed there is any scientific evidence to say that any/all are beneficial. It is an elegant solution that will look the part in a clean sophisticated way.
If you like, you could do without the MFD plinth and just use the Sorbothane feet attched directly to your equipment, or you could substitute the MDF for black marble pieces that would add a look of quality and style.
If you were insistant on utilising the suspension technique, it should be possible to suspend the MDF/marble plinth from the shelf above using an elastic material.
Feel free to add your comments about this design.