About two years ago I had one of those light bulb moments, an epiphany in which I realized that an ordinary Cadmium Sulfide cell (CdS cell) could be used as a light to heat converter. You see, if we place a fixed voltage across a CdS cell, it will heat up more under the exposure of light because it's resistance decreases with incident light. This is a useful invention because you can do a lot with a light to heat converter. In the images I've uploaded you will see four views of a proof-of-concept prototype for enabling blind and visually impaired people to sense images thermally with their fingers. You just place a coarse image on the 5x5 CdS cell sensor array, flip the switch on for 30 seconds in bright sunlight, then close the red missile switch off and the array will retain a heat pattern of the image for some time. Users can then perceive the image by feel of temperature. This prototype is constructed and tested working with a 6V source of four AA batteries, a switch, the array, and a few wires plus case and rubber footies. Your mission, should you decide to accept it, is to 3D print a functional object based on this principle. You can duplicate the prototype, increase the resolution, alter the power source, hook it up to a cell phone even, not to mention the host of other concepts that a light to heat converter can facilitate. I love inventing, or creating really, but I just don't have the biz and legal skills or motivation to drive a patent thru so I just gave this invention to the world in a youtube video some time ago. You are welcome to take this idea and run with it if you wish, just be sure to say "Thanks, Les!". I included a blank copy of the Customizer Template to give you a starting point. Note that all of the parts in this design were purchased from http://www.sparkfun.com which is a techie maker company of sorts, great for all your electronics needs.