Going through the upload process on Ponoko, I choose arctic ice acrylic
as the material for the light panels. Being frosted on one side means it will diffuse the light nicely.
To contrast this I choose the much darker hardboard
as the material for the top, bottom and wedges.
Once I upload my .eps files and choose the materials I want, I just need to click 'Make', enter in my delivery details and wait for the package to turn up from Ponoko.