Buh. Wholly missed the point: that's really cool. I've always wanted to sit down and do that. I've done it with aluminum but that's different because it's not really useful. The chisel you were using: what was it like? Single or double bevel? Roughly what angle was the tip? I've read about people using glass to do this, or brazed carbide toolbits, but I didn't actually get a chance to talk to them about it.