[chromationsystems] put out a couple instructibles on building infinity mirrors. One with an 8×8 array of LEDs and one with a 32 LED ring. These are very well  documented covering the construction of the mirror enclosure as well as the circuit and code. The effect is quite nice. The 8×8 array is interesting, we haven’t seen that before. These would make a fine addition to any geek cave/electronics lab. While it looks like these were basically advertisements for a product he sells, you can definitely make your own from his instructions. We like this kind of advertising.