I used VHT Nightshade.
My process wasn't perfect, I kind of messed up the initial part but if you do it this way it should turn out nicely.
1. Clean the lights
2. Wetsand the lights (optional, I didnt, 1500 grit, light sand)
3. Coat with nightshade (your discretion, I think too much looks tacky, I did 2 coats)
4. Wait 5-10 minutes
5. Recoat (If dark enough already, skip to step 6, if not repeat steps 4 & 5 as needed)
6. Clearcoat (Krylon Acrylic Clear Coat / Rust Acrylic oleum clear coat)
7. Wait 5-10 Minutes
8. Recoat ( You can stop here if youd like, some people like 3 though)
9. Wait 10-20 Minutes
10. Wetsand with 2000 Grit lightly
11. Apply rubbing alcohol, rub lightly on light covering whole light, allow to dry
12. Apply buffing compound, thin layer over whole light, buff.
13. With a microfiber cloth buff RAPIDLY until shiny.
That is for a gloss look, if you like the Matte, simply stop before clear-coating, sand with 2000 grit, and apply rubbing alcohol lightly. (I'm not sure if buffing compound will take away the matte look so I will leave that up to you although it may make it a little cleaner looking)