The project is open source, both hard- and software, so people can build their own units or improve them as much as they like. At the same time, I'm hoping to produce a few runs of sensor units so people without all the necessary production means can get a unit or two.
Check out the GitHub repository for the source code. I'm using the Arduino IDE to program the ESP8266 WiFi microcontroller. The README is a bit out of date, and there aren't any hardware design files in the repo yet, as it's all still just put together on a WeMos D1 arduino compatible board.