His technique relied on stipple engraving to achieve subtle gradations of light and shadow. Instead of using long, continuous lines, Copia applied thousands of small dots to the plate. This method captured the atmospheric quality of charcoal drawings. His portrait of Jean-Paul Marat is a clear example of this style. It presents the revolutionary figure with a stark, sculptural quality that avoids unnecessary ornamentation.

Modern collectors value these engravings for their historical weight and clean aesthetic. The monochrome palette of his work provides a neutral yet sophisticated element for interior spaces. These engravings represent a specific moment in French history when art became a tool for civic identity. A print by Copia brings a sense of intellectual history to a room without overwhelming the existing decor.