Holes in glass are made using a drill with a diamond drill bit that is constantly cooled with water. The process can be carried out manually or with CNC machinery, and the technique used can be performed using a single-head drilling machine or a doubled-head machine which shortens fabrication times and reduces stress on the glass. A minimum distance from the edge should be observed when drilling to prevent breakage caused by internal strains that may occur during the tempering process. This distance depends on the thickness of the glass. A hole along an edge should be made at a minimum distance equal to double the thickness of the sheet; for a corner hole on the other hand, the distance must be four times the thickness and is measured from the tip of the corner to the nearest edge of the hole. Again, for technical requirements connected to tempering, the diameter of each hole must, as a minimum, be equal to the thickness of the glass.