Very clever; but what if it rains.
Since they are all filled with the same quantity of liquid, they will all dilute and overflow by the same amount, thus not changing the differential shades, so any photographs of them just need the black point dragging down a bit I reckon.
Mind you, might make 'em cold
Cheers,
Hope they used decaffeinated coffee as I wouldn't like to think of Lisa becoming a moaner ("Mona") because of an upset tummy, headache, etc. brought on by excessive caffeine in the system! ;-)
I cannot imagine a valuable use for time spent - except maybe sand paintings. If we have enough cups and enough coffee, we won't need our digital sensors anymore....
I'm surprised the coffee could last. I could use some free drinks!
The aroma must have been very tempting.