Lexan can be bent, easy or hard. Officially, you should bake the sheet on the form you intend to shape it over. Preheat it to 200+ degrees F for some time to drive out the water. Otherwise the vapor forms bubbles. Then increase the heat, long enough to reach the interior, and bend over your form. You should also use a layer of flannel over the form to prevent scratches.
Unofficially, bubbles and scratches help disperse light and prevent the directionality problem. Just heat and bend.
And feuss2 is correct- there is no such thing as a white LED, really. LEDs are about as monochromatic as a laser, which is to say pretty f'kn monochomatic. "White" is synthesized by mixing two or three colors, and even then it's a pretty cheesy white. Since the plastic lens cover will filter out anthing but broadband red, there's no point. Incandescent bulbs produce white by emitting the whole spectrum, which is why a red lens is needed. If your LEDs are weatherproof, you could just rig this thing with red LEDs and ditch the plastic lens cover entirely. Notice that lots of modern sportbikes use LEDs with no "lenses," or at least just a clear windscreen.
So feuss2, how much are the LEDs themselves? Can you do a bulk purchase if enough people sign up?
Rene Carlos