Drypoint is a traditional fine-art printing technique. Basically you scratch a design with something sharp into a smooth surface. This is the printing plate, and could be a metal such as copper or zinc, or a piece of acetate, or even cardboard. You then coat the plate with ink (usually oil-based as it dries slowly), wipe the plate with fabric (scrim) so ink remains only in the scratched groves, then print the plate.