I have always wanted to have light upstairs and thought that under the railing would work. Using U Shape LED Aluminum Channel (https://www.amazon.com/gp/product/B01M09PBYX/) and RGBW LEDs, it creates a fun mood on the stairs. While the system doesn’t have motion sensing, it mostly only turns on when the house is in party mode or movie mode. Power splicing and terminal block are hidden in additional CU-18428-W.
Part of the prototyping was using a Uno to control the LEDs test patterns
This was before the cable management was installed for power splicing:
The box in the top left hosts the ESP8266 control board, The bottom box is where the power comes in and is distributed to the next 2 boxes along the right: