Like tokinballer said, ask the manager at a headshop, or ask some local glass blowers about getting custom work.

But be prepared to pay a ton of cash. Custom pieces do not come cheap. I got a custom glass spoon made a few years ago. It was a very small spoon, but it still cost me $45.

But sadly, it broke last night. I don't mind though. I accidently broke the bowl hole and made it too big. I put it away and last night I was cleaning some lint that got in the carb hole. Then that broke a huge chunk, si I tossed it.