I had been wanting to build something like this for some time, but didn't have the impetus until given a class project for a chemistry lab. We were tasked with recreating an instrument from the lab and I chose to mimic the UV-VIS. While I did not incorporate a UV or IR LED in this project, it will scan from 380 nm to 780 nm. Recording light intensity into an array allows for easy output of absorbance values (after a calibration run). The switch toggles between calibration and determination modes and the button starts the cycle. The LEDs on the top of the box are status LEDs. Inside the box are 2 RGB LEDs and 2 LDRs. Check out http://bradmartinscience.com/minispec for the full story.