The lines for copper foil and lead cartoons need to be of different sizes. Only a small width is required between glass pieces in copper foil. This allowance is for the two thicknesses of foil and a space for the solder to run through from front side to the back side. In leaded glass a wider line is needed to allow for the width of the heart of the came.
On cartoons for different methods, draw the lines in the appropriate width. For copper foil this width is ca. 0.8mm. This can be accomplished with a ball point pen or fine felt tip.
For leaded glass panels, a thicker line of ca. 1.6mm is required. A bullet tipped felt pen is usually appropriate, if it is not worn down at all.
A cartoon for fused glass should use the finest line possible, as the glass pieces will be in direct contact (ideally) with each other. As in copper foil, a ball point or fine felt tipped pen will be appropriate.