Re: Base grind
If you want to do anything to glass, you have to find a way to keep the glass cool. Thats for drilling or grinding. Otherwise it will break. And uniless the tools are speciffiacaly made to cut glass you will need to go very very slow. Too much pressure and smash.. I had to drill holes into large galss bottles with the thick bottoms. Lots of broken glass before i got it right.
(*Disclaimer* These are my opinions and mine alone. It does not reflect the opinions of others and is based on my personal smoking enjoyment and experience)