This is quite a unique type of filament I'm not sure what the exact application would be for using this, but I'm sure there is something. It's a UV Sensitive ABS 3D Printing Filament, which turns a reddish pink color almost instantly when placed in UV light (The sun). Once it is taken out of UV light it will change back to the cloudy white/clear color within a couple of minutes. This filament is sold by Makergeeks for $19.95 per 1/4 pound spool. Check it out, and watch the video below:

http://makergeeks.com/uvseabs3dprf.html