I printed the jet engine with the parts colored by function, so I needed a descriptive little legend plaque.
I printed 1/2" tiles of each color, and a thin sheet with insets for them. I printed the text with a Brother P-Touch using 1/2" tape with a clear backing.
I've included the FreeCAD files so people can adjust it to accommodate different size text or more/fewer colors. When you're ready to create the STL file for the plaque, click the pocket labeled "export this" and use File -> Export.
I've also included parametric openSCAD files, where you can change the tile count/size/etc directly, which is probably easier than messing about with the FreeCAD file.