What you need
Glass Cutter (TechShop)
Cutting glass is really easy to do. There are just a few tricks that you need to know.
Getting you glass cutter ready. I use an oil glass cutter. The oil helps proctored the cutting edge and run smoother over the glass. When filling the glass cutter, only put in what you need. The oil will leak out and you will waste oil. You can buy oil at a local stain glass store, or on-line and the small bottle will go a long way.
Step 1: Scoring the Glass
I cut glass to fit into a frame that I made. You want to measure and mark that glass; I used a Sharpie to mark the glass. I had a piece of Masonite that I used as the straight edge. When you line up the straight edge beware of the off set of were the cutter wheel is too the side of the cutter. Holding the glass cutter like a pencil, holding the straight edge in place, score the glass with firm pressure. Only make one pass with the glass cutter, never making two pass with the glass cutter. When scoring the glass you are making a weak point in the glass.