These are really only needed when the glass is so dark that a light table does not transmit sufficient light through the glass to see the cartoon lines. An alternative is to cut at the side of the cartoon lines, leaving the appropriate sized pattern piece.
Pattern shears are specially designed three-bladed scissors that are used to cut out patterns. The middle blade cuts out the allowance for the heart of the lead came or copper foil. Different shears are available for lead or foil work. The allowance for lead came is usually 1.5mm; foil allowance is 0.75mm.
Knives with two parallel blades properly spaced for the lead came or foil allowance are also available for pattern cutting. These are ideal for tight curves, as they are easier to manipulate than shears.