When I told my friend Bill Tosh that I was looking for large, plastic beads to use for parrel beads, he told me about some plastic balls that he had. He was able to drill a 5/16 inch hole right in the center of each of the solid plastic balls. I don't know what kind of plastic these are and neither does Bill, but it is tough and will not shatter. Bill says they were supposed to be used in roll-on deodorant bottles but that he got a box of them for some reason that he has forgotten.