Alexxai Kravitz has generously shared the following regarding FED, part 2:
The Feeding Experimentation Device (FED) is a free, open-source system for measuring food intake in rodents. FED uses an Arduino processor, a stepper motor, an infrared beam detector, and an SD card to record time-stamps of 20mg pellets eaten by singly housed rodents. FED is powered by a battery, which allows it to be placed in colony caging or within other experimental equipment. The battery lasts ~5 days on a charge, providing uninterrupted feeding records over this duration. The electronics for building each FED cost around $150USD, and the 3D printed parts cost between $20 and $400, depending on access to 3D printers and desired print quality.
The Kravitz lab has published a large update of their Feeding Experimentation Device (FED) to their Github site, including updated 3D design files that print more easily and updates to the code to dispense pellets more reliably.
Feeding Experimentation Device (FED) is a home cage-compatible feeding system that measures food intake with high accuracy and temporal resolution. FED offers a low-cost alternative (~$350) to commercial feeders, with the convenience of use in tradition colony rack caging.
KravitzLab has shared the Arduino scripts for controlling FED, as well as, the python code used to analyze the feeding data collected by FED on the KravitzLab Github. Additionally, build instructions and power considerations are detailed on the FED Wiki page and 3D Design Files provided through TinkerCAD.