Warning: This project contains sharp edges of broken glass and fire. But if you are careful, you'll like it.
1. Select the beautiful but tight bottle. Tie the thread tightly around the bottle just above the label.
2. Pull the thread and dip a flammable liquid. Keep your hands dry.
3. Pull the thread back into the bottle and ignite. Keep the bottle horizontally and rotate until the fire spreads. Wait clicks, about 10 seconds.
4. Pour cold water on the thread. The top part of the bottle fall off.
5. Process the edge to smooth state.
Source:
www.collegeenvy.com