Hi Lex, shore hardness is definitely an important factor when choosing a vibration dampener, but it’s not the only one. The materials’ rebound resilience, resistance to chemicals, UV radiation, and moisture are all important. Rubber is most commonly used for this application. I understand that if you are making your own dampeners, it is easier to print a mold to cast silicone or polyurethane as rubber parts require specialized tooling to produce. In general, silicone generally has lower shore hardnesses, while having excellent thermal resistance. Polyurethane is tough, and abrasion-resistant, and can be produced in many shore hardnesses but can suffer from water ingress. Rubber is cheap, and resistant to water and oils but custom-designed parts cannot be cheaply produced in small volumes.

 I can also provide some guidance on a shore A hardness range. In general, you want the material to be quite soft but not too soft, typically between 20A and 50A. Note that most rubber formulations are between 50 and 65 shore A whereas silicone tends to be on the lower shore hardness scale, up to about 40A. Polyurethanes can be anywhere from 30A up to 100 A (And can pass into the harder shore D scale as well.) You will, unfortunately, have to test which material is best or delve into the complexities of vibration calculations.