baby i can see your halo ...la la la

[Flaminpyro]

Or you could use light pipe and put in any color you want through it, it's available in many diameters so you should be able
to find a size that works for you and getting a perfect circle is not a problem but the over lap at the end will have
to be dealt with. In smaller diameters it's called fiber optic cable.

here is one example>


http://laserpointerforums.com/f38/car-audio-project-405-lightpipe-77398.html#post1113091

Good luck...