I have built various iterations of the reflection illumination module and case over the past weeks. The biggest challenge I encountered was to improve the image quality, especially reducing [vignetting](https://en.wikipedia.org/wiki/Vignetting). The most important issues I've encountered were with the LED. Most notably: 1. The clear lens that comes with most LEDs causes non-uniform illumination of the sample. 2. The required luminous intensity matters a lot. Regarding 1: A diffuse lens LED with a high enough luminous intensity is hard to find. I ended up making the clear lens diffuse with sandpaper, which worked surprisingly well. Regarding 2: The [currently suggested LED](https://build.openflexure.org/openflexure-microscope/v6.1.5/docs/#/parts/electronics/white_led) (NSPL500DS) is rated [22 cd](https://nl.rs-online.com/web/p/leds/7133983/). In my experience, a stronger LED helps with the image quality. I ended up using the C503D-WAN-CCBEB151 ([65 cd](https://nl.rs-online.com/web/p/leds/9199792/)). Adding this information to the documentation for the White LED part information ([docs/parts/electronics/white_led](https://build.openflexure.org/openflexure-microscope/v6.1.5/docs/#/parts/electronics/white_led)) could save people some work in the future. I'm currently finishing up a merge request to add this information to the docs. I hope you will be able to merge this. I'd be happy to make further improvements to this pull request where needed.