Just about done with the control board schematic and PCB design..  As I mentioned previously, I am going with a multiple option approach....  One option will allow you to just buy the breakout boards from ebay, etc. and solder them right onto the carrier board..which will make for a quick and easy solution..  The next would be to just buy the components and the nucleo board, drop them on and solder them up..  The first option would probably require two boards since the breakouts take plenty of space..  But it looks pretty good for fitting everything onto one board with the bare components..  

Here's the option#2 with the bare components..after I fix a couple routing problems and such, I'll start with the carrier board for the first option..

This board allows the raspberryPi to offload the hard work to the nucleo...Opening and closing the cuvette tray/door..changing the 522nm and 550nm edge filters, monitoring and controlling the cuvette temperature, monitoring current draw from the peltiers, turning the laser on and off, controlling the laser shutter, and a few other functions..  It will talk to the raspberryPi through RS232 since the nucleo already has a nifty USB serial port..