I feel like the ribs are shallower than some people think. The DS2 hangar set photo has a nice, strong overhead light source that shows them up nicely. Is the one geordietrooper took pics of in the Archives the same as the exhibition box? That is, did more than one get the upper left square painted red? And, if so, when and why? It was never that way in any of the OT films that I've noticed. And I can barely see the ribs on the MoM box.
The relief-comparison that overhead lighting allows shows the blue square to be a good double the thickness of the ribs. Their shadow is far fainter. Also, Piero has them extend all the way to the edge, past the rockers, when it looks like they not only end at the rockers, but taper down to them. Those end "riblets" he has on his past the rockers aren't there on geordietrooper's other Archive pic from that angle, for starters. But in general, the ribbing is less pronounced/shadowed next to them, and there isn't even slight ribbing visible in that original Elstree dress-up photo RBJ started out the thread with, or the higher-res running-through-the-halls pic. Even if the contrast is such that one couldn't see the ribs, if they're of uniform thickness, you'd see them against the first rocker. And we know they're there on the ANH boxes (and why I think the same half-dozen were re-used for the ROTJ hangar scene, rather than new ones made) thanks to that TIE fighter cockpit set photo.
To my eye, the ribs are only in the middle third, between the pinstriping and the rockers, and go from maybe 1/16" at most down to the flat background right where the rockers mount. I'm loving this thread. I'd gotten frustrated at my own researching into the exact detailing and proportions of things because of the paucity of decent high-res, high-contrast pictures or footage. Those Archive pics help a ton, geordietrooper. Thanks for posting them.
From what I can tell ONE box got the upper left tile painted red. It’s the MOM box and the one in the archives pics. You can see the red paint on the edge of tile next to it.
I’m fairly certain it is the same box in the hangar shot but not sure.