I have a cabinet from Tip and have used sand,glass beads,coal dust and ground glass. I have to disagree with david here, it all will take out the glass as well as creating dust. Some more,some less, sand is by far the worst. My glass has a piece of mylar plastic on the inside of the glass, held on with double sided tape, which has to be changed quite often. I was told at Tip that if you attach a piece of window screen on the inside of the glass, it will greatly extend the life of the protective plastic. The particles hit the screen and bounce off before they can cloud the glass. The screen is so close that your not suppose to have any problems seeing through it. The Tip store is about 10 miles from my house and I go there often. I haven't tryed it yet,too cold, but the guys at Tip have always been helpful and generally know what they are talking about.
Also if you a shop vac with out a fine particle filter, you will destroy the vac motor in a short time. They just can't handle that fine sand.