Lego Spectrometer (2017)
publiclab.org
publiclab.org
There are also a number of spectroscope enclosures on thingiverse, but it's always so hard to gauge if any of the projects are actually worth printing. The most dead-simple and cheap example I found used the same slit/CD plastic combo capped onto the ends of a paper towel tube.
Some other stuff[2,3,4]
https://github.com/leswright1977/PySpectrometer
https://www.youtube.com/watch?v=jAV7bnNrE-M
https://physicsopenlab.org/2021/06/19/absorption-spectroscop...
Also interesting, and even cheaper, is a paper spectrometer which attaches to a phone camera by the same designer as this Lego one [1].