This thing uses:
http://www.banggood.com/0_96-Inch-4Pin-White-IIC-I2C-OLED-Display-Module-12864-LED-For-Arduino-p-958196.html
...and:
http://www.banggood.com/D1-Mini-NodeMcu-Lua-WIFI-ESP8266-Development-Board-p-1044858.html
...to display any string from a MQTT topic. Use for example https://mosquitto.org/ and http://nodered.org/ to compose/broadcast a text. The program for the ESP8266 is included and you can change font, topic, server etc. as you like and recompile using the Arduino IDE.

N/A

Yes

Yes

0.2

20%

1. Solder long flexible wires (e.g silicon) between the OLED the LED and the ESP8266 PCB.
2. Solder the button.
3. Load the program in to the ESP8266 using Arduino IDE and check that everything works as expected.
4. Glue the OLED (using a heat glue gun) to the box.
5. Mount the LED in the box.
6. Use a double-sided tape to fixate the ESP8266 to the bottom part off the box.
7. Mount the bottom to the box using heat glue