Imagine battery operated RGB LED light everywhere in your house that auto-connects to your wifi and that you can control from your computer or any smartphone! Simple to program and change color or RGB LED effect. It uses WS2812b LEDS. It has embedded motion sensor and ambient light sensor!
Idea is to use only few components and keep cost minimal...
about $2 for ESP8266
about $3 for LED light with housing and PIR Human Body Motion & Light Sensor
about $4 for 16 Bits 16 X WS2812 5050 RGB LED Ring Lamp Light with Integrated Drivers FZ1558
Overall sub $10! But you get embedded web server and battery operated RGB LED mood light that you can control from any device in your house (or outside/remote if you have VPN)