Working on a tumbler, medium size. have a smaller one but it's more of a prototype figure it out deal.
glass is 6 to 6.5 on the mohs scale but also weaker the larger and thinner the piece. the thick bottoms would be the choice pieces
tempered glass is the best for tumbling but no reason you can't use that thick stuff, to fast and it will drop causing lots of cracks and chips in the glass. large pieces also help with keeping down the chips ext. gonna have to play around to get smooth clear pieces that is the challenge with every type of material put into a tumbler right?
Here is some ran with garnet,water,sugar and coarse grind as the media.
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this is after three days of running.
after that tone down the medias to a polish media until you get the results you like.
Edit If your hard up finding garnets and coarse grind you might want to try crushed up grinding wheels. some of the glues used in the wheels can cause problems but the price is right to try a trial run.
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