Two closely spaced layers (transparent top layer) which are separated by an array of millions of tiny elastic blobs - as pressure on surface increases the blobs spread out, thus the colour of the surface changes.
The colour of the elastic blobs is opposite the colour of the bottom layer to maximise the colour changing effect.
This is not actually paint, so suggestions for better category are welcome.-- xaviergisz, Nov 10 2006 Variable filter double glazing Variable_20filter_20double_20glazingAlternative technology which this idea could also use to create colour [hippo, Nov 10 2006] air resistance meter real_20time_20air_20resistance_20meterinspiration for the idea [xaviergisz, Nov 14 2006] Liquid crystal?-- Ling, Nov 10 2006 [Ling], I thought about using a light attenuating liquid between the layers, but then I thought this would cause pressure in one area of the surface to effect pressure in the other areas.-- xaviergisz, Nov 10 2006 A variation to this idea could be illuminated.
the bottom layer is an optical wave guide (like a sheathless optical fibre) with internally reflected light. The blobs are also transparent, so as the blobs are squashed they contact more surface area of the bottom layer thus 'tapping out' more light.-- xaviergisz, Nov 10 2006 I like the method of this idea, but have to ask how the effect will be seen through whatever is pressing on the surface. Maybe it will have to be viewed from the other side, or through clear liquid.-- baconbrain, Nov 14 2006 My skin changes colour according to pressure.-- Chefboyrbored, Nov 14 2006 ah, good question baconbrain. the link should explain.-- xaviergisz, Nov 14 2006 I like this. The color change should surround the object placed on the surface, with the bottom color most prominent closest to the object and fading outward, like an aura of sorts.-- Shz, Nov 14 2006 random, halfbakery