Glass from glass bottles. A bar down the street named 'The Hut' Tucson Az. donates weekly to our effort, as well as friends and family. After we receive the bottles, we wash off the labels. Break up the glass and then cast the glass in a slab. After the slab cools, we cut it up into cubes, and then hand grind a roundel shape out of them. At this point more grinding is done until the final shape is acquired, and then a final polish in the tumbler.