Hi Mark,
Thank you for your interest in our Big Rock platform.
We use a special order material as the Plinth (top plate) and depending on the specific model, the Big Rock's Plinth can be up to six layers thick. All of our vibration control platforms - Big Rock, IsoRock and Air Mass - use multiple layer construction and constrained layer damping as do the Little Rock pods that are placed on top of equipment.
We do have a number of factory-direct specials available that are quite affordable. Please contact me directly if you are interested. That will save you considerable time and avoid the "hit or miss" inevitability of a DIY version of an established design.
Best Regards,
Barry Kohan
President
Bright Star Audio