Please watch this video demonstration:

This project consists of a double-sided PCB with headers for four LED matrix displays and an Arduino Pro Mini. The rest of the component can be soldered directly on the PCB (two momentary buttons, a slide switch, and a barrel connector).

You can use this gadget as a display. I plan to use it as a Pomodoro counter, with one button assigned to timer mode, and the other to reset the time.

This PCB is also a platform on which anyone interested can design new features. For example, I plan to add a real time clock so my gadget can display time and date, a programming header (so I don't have to remove the Arduino to program it), and a buzzer so that it can make some noise when the timer expires.

I created this PCB as part of my KiCad Like a Pro course. It gives the opportunity to practice precision measurements and implementing a user interface using a PCB.