Arduino BLE Time Hacker Clock
A Time Hacker Clock is a device based on the Time Hacker Method (THM). THM combines simple productivity guidelines with devices that emit shapes or colors to quickly convey how much time remains in a given day or time block.
This version of the clock uses an Ardunio based microcontroller to light a plastic dome.
The colors used are from the HSV color space, essentially the colors from green to red in a 120-degree range. A green light represents having more available time and a red light indicates the available time is expiring.
The clock is powered by a small battery and controlled using a mobile app (Android / iOS) via Bluetooth.
Review these docs to build your own version.