A glass cutter is mainly used for cutting large glass and window panes. Breaking glass is easy when you have the right tools. To get the glass to break straight right at the spot you want, you need to score it with a glass cutter. Press the cutter firmly against the glass using a straightedge or something similar to help, and make a score in the glass. You can break the glass along the score by pressing down on both sides of it. Quality glass cutterBlade options: 2, 3, 4, 5 and 6 mm