Libra Cervisiae is an ESP8266-powered microcontroller for reading output from a high-precision scale, used to weigh beer to measure the progress of its fermentation.
Development updates can be found at the project's github pages site.
Libra Cervisiae used to be Pendulum, which was itself once a tilting hydrometer (abandoned for patent reasons) and once a weigh-a-sinker hydrometer (abandoned for DIY difficulty reasons).
Libra Cervisiae has its root in experiments done in the 1990s on measuring fermentation progress by CO2 production, and more recent experiments done by forumgoers at Homebrewtalk and Hobbybrouwen.nl.
Libra Cervisiae is a microcontroller and PCB project. The project is designed with easy DIY in mind, and as such, the PCB uses large, easy-to-solder surface mount components, as well as breakout boards for the major, non-ESP8266 integrated circuits.
The project as specified here includes building a scale of your own, but the microcontroller's design ought to allow for hacking existing scales of the correct capacity, too.