Optically variable security devices, including security threads, patches, labels, strips, are disclosed herein. Certain security devices according to the present disclosure utilize a lens-less construction whereby multiple icon layers are coupled to produce a synthetic image or synthetic color that has an optically variable effect. Each icon layer includes an array of high-resolution icon elements that are aligned relative to each other and spaced apart from each other to produce the desired optically variable effect. Such security devices are particularly, though not exclusively, useful for authenticating security documents.