A device includes a substrate and at least 1,000 flakes resting upon the substrate, each flake including a magnetic layer. The plurality of flakes are aligned so as to form a plurality of rings or curves, wherein within each ring or curve, flakes are tilted at a same angle with respect to the substrate and planes extending from surfaces of said flakes intersect with one another. The device provides a visible image of a single ring or curve when illuminated with a single light source, and three rings or curves are visible when three light sources illuminate the device. The device may be used as a printed light detector.