How to cut bottles for building decoration

First, fill the bottle you want to cut with water to the depth at which you want the cut. (Note: clean water works too!)

Next, attach a wire with a bit of cloth or wick material around it at the water level.

Soak the cloth with kerosene.

Burn the cloth...



When the fire goes out, the glass should have cracked owing to the temperature difference across the glass from inside to outside.


With practice you can reliably get clean cuts right where you want them.
Photos courtesy Tai Power Seeff (taipowerseeff.com).