You have an ESP8266 board like the Wemos D1, a Li-Ion battery ... Well then, does [Mads Chr. Olesen] have a tutorial for you! Here, you’ll learn the quick and easy way to get your sensor ...

So they decided to base the guts on common components that can be put together easily, specifically a Wemos Mini D1 with an OLED shield as a bright display. They also designed a cool tiltable 3D ...