Have you thought about acrylic? I saw a couple years ago in cayman islands a light hung with acrylic and when light went through it it was pretty much invisble so it looked like the light was floating. I don't know if you would be able to do it with the way you want to hang your light. Its still a pretty cool idea though.
On a separate note I agree with the guys saying to router it in then add aluminum where you can't see it.
Good Luck !!
