Start by scoring the bottle at the height you want. Take your time with this step.

Place some towels in the sink or a plastic bucket with some water inside.

Pour boiling water on the score mark, while turning the bottle over the sink.

Then run cold water on the score mark while turning the bottle again.

Sometimes it will break right away. Others required a few repeated steps of boiling and cold water.

You may hear a crackle and then, boom, the bottom falls into the bucket.

Sand the edges with the paper that comes with the bottle cutter.