After doing some hacking on the default display of an ender 3 v2 (see
Z-position display hack thread), I learned what the 9.ICO file is.
If you want to change display icons, the 9.ICO file is a container that contains 91 separate JPEG images that the firmware and display use to draw the UI. It's not a standard Windows .ICO file, but serves a similar purpose.
I've created some tools to extract the files from the 9.ICO file, which allows you to create your own should you want to. The tools also do the inverse, making a new .ICO file from a directory of images.
This is a pretty niche tool, but if you are interested in doing your own display hacking, check it out.
On github:
dwin-ico-tools
