Cutting glass might seem difficult and quite terrifying actually but there are some easy methods to cut a glass bottles in your desired shape.
Score the bottle. Use a glass cutter or a glass drill bit to score a line.Find a support system to hold the bottle in place and draw a perfect line or just freehand it if you have a steady hand.
Heat the bottle. Heat the line that you made with the glass cutter. You can use a small candle or a small butane torch. Focus the heat directly along the score line, and constantly rotate the bottle to get even coverage.
Dip the bottle in cold water. After 5 minutes of heating the bottle, dip the end you are breaking off in cold water. Add optional ice to the water.
Repeat the process. The bottle might not break on the first try so repeat the heating and cooling process until you get the bottle cut.
Sand the edges. Use a rough square of sandpaper to clean the glass edges until you are certain you will not cut yourself on those edges.
Cutting the bottle with yarn
Wrap your yarn. Select the cutting line ans wrap yarn around it 3-5 times and tie it well.
Soak the yarn in acetone. Soak the yarn in acetone or nail polish remover.
Wrap the bottle again. Make sure the yarn is placed in the right position and held together very tightly in order to obtain that fine clean cut.
Light the yarn on fire. Set the yarn on fire and rotate the bottle slowly to get the fire spread evenly.
Dunk the bottle in cold water. Dig the bottle in the water after the fire has gone out . Use ice in the water. The bottle should break perfectly.
Sand the edges. Sandpaper the edges until it is smooth and clean.
