The UVEX-3 and UVEX-4 are open source Spectrograph projects from "The Nice people" in France. The main optics design was done by Christain Bull.
At present, finding their web pages in the US can be challenging, and most of them are in French. Using google Chrome or Chromium allows for translation which works very well. The links to all of the pages are in the tables below.
In order to download the STL files, you have to click on them one at a time, very teadous considering how many there are. Downloading this git repository gives you this documenation and all of the STL files in one shot.
for more information refer to https://msproul.github.io/UVEX/