Kind of like when I got those Multiplying Soap Bubbles and found out they weren't really soap bubbles... damn things were plastic!
QUESTION: How many times do you think you'll have the thread break just in rehearsing this?
A real "glass" ball will probably prove to be too heavy to work with, compared to the plastic and a heck of a lot more expensive to have to replace every time you drop it as the result of a broken hook-up and gravity.
Now it's not impossible to show a real glass ball at the start and close if desired (though I feel that's gilding the lily)... the audience will percieve it as being either glass or, if you have bubbles everywhere, they'll think it a big bubble (especially if you treat it with a mother of pearl iridescent glaze)
Your posts, the one's I've looked at thus far, denote someone that's not looking at this sort of magic from a realistic point of view. As I've said before, I'm not picking on you, but I believe your expectations are filled with a great deal of fantasy, if you would. As I said before, you need to invest in books and even some instructional video (not how to do tricks but more on the mechanics around magic -- slights, thread work, top-its, etc.) Learn the basics and get a foundation under your belt so that you're not as disappointed when you get these things. Know however that you're not alone, we've all had our "visions" around an effect shattered when faced with reality. In the case of anything that floats, the real magic happens when you learn to work with it and create a style of choreography that makes it defy all assumed aspects of logic. You purchase the trick but it's up to you to make it magic
