These seven-segment displays are 6 inches tall and come in five different colors. The digits are controlled with a serial shift register interface, so multiple segments can be daisy-chained. Any number of segments can be controlled with three pins from an Arduino, Photon, or other controller. For more detail, check out the project on the Reclaimer Labs website. <a href="http://www.reclaimerlabs.com/seven-segment-display/" target="_blank">http://www.reclaimerlabs.com/seven-segment-display/</a> <a href="http://www.reclaimerlabs.com/blog/2015/3/3/prototype-clock" target="_blank">http://www.reclaimerlabs.com/blog/2015/3/3/prototype-clock</a> <a href="http://www.reclaimerlabs.com/blog/2015/5/5/using-an-arduino" target="_blank">http://www.reclaimerlabs.com/blog/2015/5/5/using-an-arduino</a> All design files, including example firmware, are available on github. <a href="https://github.com/AscendedDaniel/clock" target="_blank">https://github.com/AscendedDaniel/clock</a>