I haven't tried this, but after reading through the awesome threads with nail polish and stickers, it occurred to me that you might be able to use automotive paint. A long time ago I saw a couple of vehicles that had paint that changed color depending on the lighting, so I thought I'd check a search engine for what's out there. There's stuff! 
For something affordable, there's Dupli-Color Mirage from Auto Barn which goes for twenty bucks a can.
Big spenders might want to try Prizmacoat from Alsa Corp which starts at eighty dollars for 4 ounces.
And for those for whom money is no object, there's Xposures ® from Alsa Corp which goes for three hundred dollars 8-o for 2 ounces, and would turn your battery into a mood battery that changes color in reaction to temperature change.
Happy modding, and I look forward to seeing photos if any of you try any of these.
Sorry I couldn't provide links, but my post count is too low yet.
For something affordable, there's Dupli-Color Mirage from Auto Barn which goes for twenty bucks a can.
Big spenders might want to try Prizmacoat from Alsa Corp which starts at eighty dollars for 4 ounces.
And for those for whom money is no object, there's Xposures ® from Alsa Corp which goes for three hundred dollars 8-o for 2 ounces, and would turn your battery into a mood battery that changes color in reaction to temperature change.
Happy modding, and I look forward to seeing photos if any of you try any of these.
Sorry I couldn't provide links, but my post count is too low yet.