Best T/T Pods/ wood blocks to eliminate vibrations

My table is 3 feet from the right speaker. When the tonearm is in play, knocking on the table plinth or dust cover creates an amplified thumping sound. The table is a Rega P3-24 and has THREE rubber cone feet that are not removable (There are two in the front and one support in the middle at the back of the T/T. The table sounds good, but I know that feedback is degrading the sound. Need recommendations for either footers, pods, points, or blocks to eliminate that thumping sound. BTW, I can not use a wall shelf because the walls are concrete, and also cannot be drilled