I actually painted the top of the light first, but it didn't look very good as there is usually a big depression and the light catches the angles. So I took what I had laying around, a piece of .093" thick plexiglass which I was experimenting with for my headlight project. The thickness matches perfectly. I laid it out and cut it a bit oversized. This is how I did it.
I backed the car up as close to a bench grinder as I could. The whole process took maybe 30-40 trips back and forth test fitting it on the car.
I then took off small sections at a time, rounding the corners as I went.
I made the factory straight cut on the plexi be the back edge, so it was nice and straight.
I slowly grinded the plexi piece to size and once it was getting close I beveled the lower side of the front and side edges to make sure the plexi would slide up and get as close to the seams as I could.
I used a fine file and a wide diagonal angle to file the 3 sides to make sure they are very straight and not wavy. The bench grinder can cut fairly stright, but it will still have some wavyness to it.
I lined up the back edge to the edge of the spoiler, not the brake light.
You'll notice that the brake light has an edge that sticks out a bit further than the spoiler.
Once I had the plexi all ready to go, I laid it on top of the 3rd brake lens and then carefully filed the red plastic lens until it matched perfectly to the upper plexi piece I made. Tape the edge of the spoiler in case you slip with the file. You don't want to nick the paint like I did. Learn from my mistake. A little black touch up fixed it as it was a very small nick.
I then added a very fine bevel to the top rear of the plexi to match the spoiler and also a tiny, fine rounding of the left and right rear corners just to keep the wash mit and chamois from catching on it.
Painted it black with clear coat from a rattle can (mask the bottom to keep paint from running under there) and used some RTV silicone to bond it in place. I later took some touch up paint and painted the red part of the lens that I had filed. That gave it a finished look.

Note that these are night pics, so not the most glamorous. It's a new camera, so I'll have to figure out how the night mode. Also, what looks like white stuff around the gap is actually light reflections.

 

Looks good! I may have to try this. Although I wonder how it would look on pewter? Thanks for the quick write up.

 

Better than it does now.

The gaps are so small on mine that I don't usually see them. It all looks like one piece to me. Then I remember that it's not. Still, close enough.
I just need to polish the black paint so it better matches the wing finish.

Here is a closeup from the rear. It's not pretty, but you also don't stick your nose right there, so it's not noticable.

 

i did something similar except painted the thing and put some letters on there to have it shine through!


oh and btw that loooks pretty good!

 

Because the light reflects off the top of the wing so much, I may just go all out and mold the top of that area into the wind and have the light still slide in and out from the rear. Then get it repainted. Then it would be awesome. Might even make the rear lens clear and mount a row of LEDs across there, as well as a back up camera.
Or maybe just get the 30th Firehawk wing. Ehh, we'll see.

 

sweet man looks good !!!