Mission One Motorcycle concept sketch by fuseproject demonstrates a variety of line weights.
Line-weight differentiation is the result of varying the pressure on a pen or pencil. With practice it’s possible to get five distinct line weights with just a normal ballpoint pen. Practicing applying different pressure is useful in creating line modulation. Most tablets have pressure-sensitive pens that simulate that same effect digitally.
As demonstrated in chapter 1, few, if any, objects have lines; they have edges. Yet designers ...