Lobo, I look for old clorox bottles in old dump that I remember about when I was a kid. Most farms in rural Penna. had a ravine running thru them somewhere on there Property. Everything ended up being thrown in to those ravines. I also found a few at flea markets. I usually abrade the sharp edge off an give 'em to people for Jewelry or make a few necklaces an try to sell them so I can buy more rock. One side of bottle points has natural convex, it,s the other side thats the problem, concave, so it,s seems like your always fighting that side to get some convex. Later Bob