This is a personal project that I am working on for my young children to start. You may consider it a prototype. The application is very simple (I think):
A mobile application which contains a single screen with various colors (Pink, Blue, Green, Red, etc.). When I tap on a color, an LED light is triggered for that color wirelessly. For example, I tap the Blue color on my mobile app, the LED turns blue. I tap the Red color on my mobile app, the LED turns red.
I suspect the wireless board will be the ESP8266 module. The eventual goal will be for this devise to be wearable, so tight and compact is key. Bonus if a setting can be put in place for the device to vibrate in addition to the LED lighting up. For now, the UI/UX of the mobile is not super important as long as it's functional to start.