I know someone who made digital candles using the technique for Hannukkah (Jewish holiday), there was a set of LEDs connected like shown in the post, and you co

I know someone who made digital candles using the technique for Hannukkah (Jewish holiday), there was a set of LEDs connected like shown in the post, and you could use your a flashlight (or a purpose built "shammash" LED) to turn each candle/LED on by touchibg it with a light, it was quite cool