SD,

A sandbox is pretty much what it says, a box filled with sand. Google "turntable sandbox" and you'll find plenty of hits. Bright Star used to make a commercial product (reviewed by Mikey wayback when) but I don't know if they're still around.

Sandboxes are also the perfect audio DIY project because they are dead cheap and dead simple to make. You'll find a host of articles describing how to make one, one of the seminal ones is the TNT Audio "Sandblaster 1.0". Anyone with basic woodworking skills and tools could knock one up and a professional carpenter should be able to make a positively beautiful one in a couple of hours.

If you are going to the trouble of having one custom made it is probably worth seeking expert advice on dimensions (i.e. depth) and the best sort of sand to use etc. You'll find relevant threads on Audiogon.

Good luck!

Follow strut's suggestions. I'll just toss in the fact that you want playground sand, not construction sand - if any of sand is exposed. If it's all enclosed or sealed in your application, then never mind, it wouldn't make a difference.

http://www.cognitivevent.com/sandbox.html

Good link. If you need racquetballs, ask any local player. We go through them fast and always have old extras. Not that they're a problem to buy new, around $2 per ball, but always free ones available, I've got a dozen in the bottom of my gym bag right now.

Target sells raquetballs and tennis balls by the bag for a few dollars. There's a difference is sound with the tennis balls sounding slightly sharper and the raquetballs sounding more mellow. You can keep them in the bag for stability or I've placed individual balls on top of a rubber Quick Cap from the plumbing department of any hardware store. Five caps/balls go under a 1 1/2" sheet of MDF (2 X 3/4" with a piece of thin non-slip carpet underlayment [or rubber mat meant for use under a kitchen cutting board] in between) and then sitting my VPI Scout on top of the MDF works well. You need only enough balls to maintain the table in a stable position when you work with it and when you push down on the table the movement is only up and down with no side to side motion.

One of my first audio tweaks was cutting racquetball balls in half, curved side down. They certainly mellow things a lot, too much for my current system. But putting them under the sandbox might move their effect closer to neutral. They are so cheap they fall into the "Why the hell not?" category. Under the sandbox you could also try an inflated inter tube for a bike tire.