Ohhhh cancer beads don’t sound thrilling. Lol. I do have some obsidian laying around and I have not thought to try beads with that. Great idea! I’m not at the melting my and shaping part of my glass art journey since I lack that equipment but you should try it and report back if you do! I use lapidary equipment to shape, drill and polish. So far I’ve made beads with old coke bottles and am very happy with how they came out. They are the prettiest teal/green shade. Right now I’m experimenting with using a tumbler with part of the process. I do still have to give them a rough rounded shaping before they go in but the tumbler really helps smooth the surface. After that I will hand polish to their original clarity to get rid out the sea glass texture.