I suppose you have to cut costs somewhere....

Outdoor unit makes noise, but noise travels up and out, not over. Problem is vibrations. Screw a metal vibrating thing into a concrete pad, vibrations travel through pad into ground, across the ground, vibrating the foundation, walls, glass, etc. of neighboring home. Rubber grommets between the metal and the concrete pad mitigates vibration. It's actually supposed to be there for all metal feet screwed into pad, but you rarely see it, causing unnecessary low frequency noise pollution, and the vibrations themselves, as far as vibrations go, are bad vibrations.

How could i diy good grommets for my house safely?