Amanda Ghassaei of Instructables has used an Objet Connex500 3D printer to add a sense of texture to photographs. The images are still meant to be viewed in 2D, but the printer uses different thicknesses to create a silhouette effect.
The 3D printer prints with a rigid, semitransparent white material that can be used to create unique black and white photographic prints. When backlit with a diffuse light, they recreate images with high precision and add subtle dimensionality and texture. Ghassaei writes:
By varying the thickness of a region of this semitransparent print you can control the amount of light that is able to pass through, thereby controlling the brightness (thinner regions of material will appear brighter and thicker regions darker). In this project, I’ve mapped each individual greyscale pixel value of an image to thickness, allowing me to precisely reproduce any greyscale image.
Ghassaei has posted images and instructions for those who would like to try it out themselves on Instructables.