I have designed the PCB in Easy EDA – You can use JLCPCB or download the Gerber files and send it off to your own PCB manufacturer.
https://easyeda.com/brettwatty/arduino-mega-8x-charger-discharger-v5
Instructable for modifying PCB boards 2.0 and below for ESP8266 WIFI: https://www.instructables.com/id/Modify-Arduino-ASCD-8x-18650-Smart-Charger-Dischar/