Best filament for conducting light

I need to design a housing that basically is a series of light pipes. Is there a filament material that’s suitable for that?

Nylon T-glass is probably best. It isn’t available yet though:

Actually it is PETT (polyester) not nylon, and it is available in 1.75mm diameter but not yet available in 3mm. This stuff is pretty amazing.

it’s not?

My bad! And so it is…