A teacher friend asked us for faster build that was less dependent on soldering because they didn't have the budget for that kit. So we've developed a "minimum  build" of the 2019 classroom logger using pre-made Dupont jumper cables (as we did in 2016) to reduce the assembly time to about 1 hour.  I've also added support to the code base for using the indicator LED as a light sensor, so they can use the logger with their existing curriculum even if they don't add extra sensors.

https://thecavepearlproject.org/2019/02/21/easy-1-hour-pro-mini-classroom-datalogger-build-update-feb-2019/

I think that Forrest Mimms work on using red &blue LEDs as a poor-mans proxy for PAR measurement is under appreciated by many researchers.