If you are into building scale model construction kits (and I used to be obsessed by the whole process), there is a problem with the paints you need to complete the job.
Essentially, a perfectly accurate duck egg blue or an olive drab coating, when applied to some model in 1/72nd scale, looks way too intense.
I’m not sure about the neurophysiology of why this is, but professional modellers know it’s true and dilute accordingly (otherwise that feldgrau Tiger tank looks black -even in 1/35th).
Today’s invention is model paints which are matched more correctly to the scale of model for which they are intended. Manufacturers could supply a separate range of paints for every scale, but more usefully a kit could be sold which would allow makers to dilute their own precisely (according to the measured perceptions of psychophysical test subjects as to which of a range of eg tanks looked the correct shade when set against images of the real thing).