His technique relied on precise line work and formal compositions. He often placed his subjects within architectural frames or oval borders. These borders frequently contained Latin inscriptions or heraldic symbols. In his portrait of the theologian William Perkins, Elstracke uses cross-hatching to create depth in the fabric of the scholar's clothing. This methodical style was suited to the demands of early seventeenth-century book illustration. He focused on clarity and detail rather than dramatic lighting or movement.

Modern collectors value Elstracke for his role as a visual historian of the Tudor and Stuart eras. His prints offer a direct link to the intellectual and political atmosphere of the 1600s. The formal symmetry of his portraits makes them effective decorative pieces for contemporary interiors. They provide a sense of historical weight without the visual clutter found in later styles. His portraits of figures like William Perkins remain sought after for their crisp execution and historical accuracy.