Recently I’ve been trying to quiet down my nomad 3. A lot of the perceivable sound was coming from the mechanical coupling of the nomad to the surface it was sitting on, basically turning the entire table into a speaker.
My first attempt was with a neoprene mat (big mouse pad) which did ok but clearly had room for improvement. Anecdotally, It reduced a lot of the very high frequency resonance but did nothing for most of the audible range. Still, it’s cheap, quick, and easy. Worth a shot.
Then I tried soft silicone bumpers. Again, better but plenty of coupling still. Seemed to quiet a broader range of frequencies but I made them custom and they just weren’t worth the hassle.
Third attempt was with a custom made pillow of sorts. The fabric was cut from heavy duty moving mats and the filling was fancy foam from an old temperpedic pillow (that stuff is gold and came in clutch during a robotics tournament once…never throw it away 
)
Better again but I could certainly still feel vibrations being transferred.
I think I have finally settled on the long term solution.
Stainless steel spikes like you would see on large speakers or in the case of the product I bought, a turntable.
My modest understanding is that the spikes act as a sort of mechanical choke point serving to decouple the machine from the surface. This sort of makes sense when we consider how sound is transferred. It’s just physically transferring energy, so a smaller point contact means less physical medium to transfer through.
I’ve also read some information describing spikes as a kind of mechanical diode. Apparently the way the spike points can make a difference, so I oriented the spike point up from the surface and placed a bit of “moon gel” under the spikes to try and further decouple. (Moon gel has been around a long while and drummers seem to love the stuff…it was cheap enough to just buy and try. Seems to work well 
)
A couple of notes:
Many spikes are made of softer materials like aluminum or copper with brass being cited as the “ideal” material because it is dampening characteristics. That’s great and all but none of the soft materials I found were rated for the weight of the little nomad…it’s got some gravity!
So I went with the most reasonable stainless steel spikes I could find (about $5 each and they come with surface protection. Not bad at all)
I also ended up putting my machine in a (very WIP) enclosure that now lives on the floor, so not all testing was done with the same enclosure on the same surface unfortunately.
What I can say definitively is that the spikes have reduced the direct vibration transfer from the suspended floor it sits on. It lives in the room above my bedroom and even on the custom cushion you could tell when it was moving and feel the ceiling vibrate if you put your hand to it.
Now with the spikes, much of that vibration is gone and the sound that still comes through is much more…pleasant? It’s not as harsh or high frequency.
This is probably a niche problem and probably only matters to a few poor souls wanting to cut brass at 10pm but I figured I’d put the idea out there for anyone interested.
Here are the spikes I purchased, no affiliate or anything it’s just to provide an example:
And the moon gel(which is not supposed to be used as a decoupling pad but again, it was cheap enough to try):
Have fun and report back if you try any of these shenanigans 
