The corners were done as an add-on for the OSS angel eyes upgrade, since the headlights are already baked open for that. If you want to do it as a standalone, it's probably not worth it.
The OSS designs angel eyes were done through AKMotorwerk's group buy. What color are you looking to pain the plastic housing? Anything can be done I assume - just gotta work it out through Luis at OSS.
Helix is doing something similar and prices are shown in their thread: