The RST Colorimeter is a device designed to approximate the functionality and results of a spectrophotometer under controlled conditions. I created it as part of a "safe", which is a large, portable physics puzzle that my team (the Rancho Safecracking Team) built as our submission to the 2016 Shalheveth Freier International Physics Tournament ("Safecracking Competition"). It consists of two small circuit boards ("SafeStamps"; a light source and a color sensor) inside of a laser-cut acrylic enclosure, with a cuvette places in the center. By restricting its usage to a small amount of substances, getting spectrum output/response data for the LED and sensor from their manufacturers, doing a bunch of math, and collecting a ton of calibration data, we were able to successfully output graphs of absorption vs. wavelength that were relatively accurate for our test substances.
Click on the pictures to the left to read about the individual SafeStamps.