Method of Protecting FDM Printed Products Based on Phase Shift of the Surface Layer

The paper proposes a method for protecting 3D printed products made using FDM technology from unauthorized copying. This method is based on the controlled deviation of the trajectory of filament application on a flat section of the surface layer of the product. The amount of deviation of the line trajectory is determined by the built-in security mark, which acts as a watermark. Changes made in this way are difficult to detect visually and even more difficult to automatically read when scanning a 3D product, and therefore hard to reproduce in a copy. In this case, the authenticity of a product can be verified by detecting a security mark: the product can be photographed with a digital camera and undergo specialized processing based on spectral analysis and narrow-band filtering.