I worked at a living history museum while I was in university and I'm still there in some fashion. This summer they brought me in to make stone tools. Today was the last day for me for the year and I was given some antique glass. Glass is wonderful to work with and the results are very nice to look at. You just have to be damned careful because with the edges being created you usually don't notice a cut until there is blood on your tools and then you get to play "find the hole and plug it" .
I believe this was the base to a canning jar.