As for sand boxes used for vibration control, I built a few many years ago. I was impressed at first, but over time the sand settled to a hard mass which ended the vibration control. I did try raking the sand, please do not make fun of me, but what a mess.
Yeah that is a misconception that hangs around so stubborn even when clearly explained it just won’t go away. Vibration control is not about isolation. Vibration control has to do with the proportional combination of mass, damping, and stiffness. The sand does not need to be loose at all to do its job. Sand packed as tight and solid as a brick still is actually better vibration control than freshly raked loose sand simply because the loose sand is softer and softer loses details. Pretty sure if you scroll up you will see where I said that already. Its just a tough concept to get across somehow.
Oh and by the way thanks for bringing it up there’s a couple more reasons to mix in a little oil. Very small amount, just barely enough to coat the grains. Eliminates dust, adds a little surface tension that pretty much puts an end to the stuff going everywhere, adds a little viscosity and lubrication that eliminates the problem of it packing down hard. I’ve got some under my turntable, and phono stage, and in my shop, been 15 years at least, consistency hasn’t hardly changed a bit. Also if you read what I wrote its not just the sand but the shape, size and material of the pad that sits on top of the sand that the component ultimately rests on that determines a lot of the control. The sand can be thought of as a stable platform on which to rest that pad or plate. That again is why its called vibration control not isolation. Or you could call it tuning if you prefer. But then you get into the whole michaelgreenaudio vague to the verge of mysticism schtick. Lets not go there.
