I often wonder if people actually read the questions before offering answers around here.
There are a couple of local glass companies that send me files to cut so they can blast. They're just etching the glass, not doing any deep carving....for that we use regular vinyl. I cut it in whatever old, leftover, or scrap vinyl I've got lying around and it's working out great for them.
If you're planning on doing any kind of depth carving in the glass you'll probably need a standard sandblast mask.
+1 I have done a lot of media blasting in a small blaster using 651 or left over vinyl. Aluminum oxide in a 70 grit and 180 grit. I havn't noticed a real differance between the grit sizes but you can cut fairly deep if you want to.
Be careful not to blast away any small peices of vinyl, like the centers of closed letters.
Don't use very old vinyl, the glue gets weak and won't hold. If you blast a piece off you can not fix it.
I also put the entire layout on the glass first and then weed, it makes it much easier to weed small letters.
I then cover the rest of the piece with transfur paper to keep it from being damaged.
I also run mine at about 80 psi.and hold the piece about 10 inches away from the gun.
Good luck, feel free to PM me with any questions