Things You'll Need
Lighter fluid or nail polish remover
String
Bowl of water large enough to hold the bottle
Goggles
Diamond-coated file

Old bottles can be upcycled into useful household items. Remove the tops of beer bottles and they can be used as drinking glasses. Remove the top of a wine bottle and you can use it as a flower vase. Cutting glass with string is surprisingly easy.
Step 1
Soak the string for a few minutes in the lighter fluid or nail polish remover.
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Step 2
Tie the soaked string around the bottle at the point you want to cut.
Step 3
Put on your goggles. Hold the bottle over a fire safe surface and set the string on fire. Allow the string to burn until it burns out on its own.
Step 4
Place the bottle in the bowl of cold water. The temperature change will cause the glass to break.
Step 5
Tap the glass gently with the back of a spoon at the break point (the point where the string is wrapped around the bottle) if it does not break.
Step 6
Smooth any jagged edges with a diamond-coated file. Be sure the glass is wet and well-lubricated when working with a diamond file.
Warning
Be sure to have a fire extinguisher nearby when working with fire. Consider wearing fire-safe gloves as well.