Re: glass bowls?
There are many glass bowls on the market and vary quite a bit in quality and design.
Most are made out of pyrex so the cracking is not an issue. They are often much more expensive than their clay counterparts as it takes quite a bit more effort and skill to make a glass bowl. If you are interested in them they can be found on various site but MNHookah.com has what are considered to be some of the best glass bowls on the market in their jet glass funnel.
If you use the search function for our wonderful forum you will find a lot more information and reviews of glass bowls. Just search for it.