I just went to the hobby shop, got a sheet of .010" clear sheet plastic and some transparent paint (I used blue in mine). A couple of coats of the paint, a little epoxy, and presto! New lenses, and cheap, too. If you wanted something a little more translucent, you could use sheets with a slight texture to them, or possibly a .005" white styrene sheet. That's thin enough to let light through, but has a slight texture to it.
