I was curious to see if I could use the filament from my 3D printers as a light pipe. The initial results are promising.
I tried two hacks to the end of the filament to try better transmit the light. One is filed to a point, the other is melted into a ball. The point seems to be brighter (though it's hard to tell in these pictures).
It does seem to leak a lot of light along the length of the "pipe".
To stick the PLA onto the LED I simply melted it with a cigarette lighter and smushed it onto the LED. BE WARNED: It appears PLA is flammable!