For a more technological solution to the copied image problem, and also the reorientation necessary throughout the year, I think you could perhaps build a very

For a more technological solution to the copied image problem, and also the reorientation necessary throughout the year, I think you could perhaps build a very large Pin Grid[1], with actuators for each pin, able to extend or retract them to the required position. Then you can figure out different patterns which are valid when lit from a particular direction, as well as altering the actual data it encodes, synchronised with updating the coupon code that merchants will accept. Could be kinda pricey for that number of actuators though, but if you were willing to have very slow update frequency, a single 2-axis adjustment head (think plotter or laser-cutter) with a smaller number of push/pull elements could move around, changing only X pins at a time, maybe with a friction lock to stop them moving once it progresses onto the next group. [1] https://en.wikipedia.org/wiki/Pin_Art https://en.wikipedia.org/wiki/Pin_Art