There were a couple things I feel I can improve on next time. The handles are just a little too narrow to fit a chain of a size that will balance the bulk of the piece. I'll use jumprings, but next time they are going to be bigger.
It isn't precisely symmetrical and I'm not sure if I can do this, but I need to try again and again before I give it up as a lost cause.
This is the biggie. When I made it, I was thinking of it as a different type of hollow bead rather than as a transparent object with a bottom that would be transparent as well. Therefore, I built up glass on the end of the mandrel and worked it back toward the center rather than working straight toward the bottom. I have removed the bead separator but am left with a rough surface where the separator was.