Adding or replacing images
You can add images to your own mod by simply putting their files in your mod's folder.
You will then need to reference those images via the correct path so the game can find them. If you use folders, which is good practice, they must be included in that path.
Here you can see the
EditorIcon node for a part in that part's
.rules file. It reference the icon's image file.
"Icon" means the image you would click on in Build Mode.
File = "icon.png"
SampleMode = Linear
Size = [32, 32]
The lack of path prefixes implies that this file sits next to the
.rules file, which is in fact the case.
The game uses PNG images.