GaryR, I used some beer bottle botoms(40 oncers do the best) and a green wine bottle. some of them are obcidian and one that looks like dacite. If you take a large nail and put it in a bottle and shake it up and down the bottom will come off pretty even. I have done this a few times and had good luck with it.
They are for decoration but I made them so they would shoot good out of a 40# bow they are 28 inches long.
Maddog