Okay, this attempt starts with rigoletto’s single-ColorRamp version here. Took some fiddling with both of the Map Range nodes to get a 6x4 grid with indexing that reached the upper right corner (if that can be done better I’d like to see it, I twitched various values until it worked, then stopped). Then a 25-stop ColorRamp, Constant interpolation (last stop is a FF00FF Fuschia warning, only shows up in the color patches if something’s gone wrong).
The patch and card borders are from sozap’s here, although I simplified (IMHO) the card border by reusing some of the patch border nodes.
This isn’t intended to be particularly flexible given that the MacBeth Chart is a standard, but both the Color Patches and thier borders are scaled/positioned off of the same Mapping node, with the card border on its own in case more padding (or whatever) is wanted. The single-face plane object is scaled to a traditional 13 by 9 inches.
MacBethChart_009.blend (173.8 KB)
@sozap , sorry but I think I’ve gotta scrub your checkmark, current hope-this-is-the-final version has too much from both of you. Wanna say again that I appreciate the ideas and help from everyone in the topic, thanks!