I smoked my lens using the same material I used to red out my taillight lens. It turned out good. It can be left permanently there but it is also can be easily removed.
Before:
http://i64.photobucket.com/albums/h1...Picture001.jpg
http://i64.photobucket.com/albums/h1...Picture002.jpg
After:
http://i64.photobucket.com/albums/h1...Picture003.jpg
Heat wrapped
http://i64.photobucket.com/albums/h1...Picture004.jpg
http://i64.photobucket.com/albums/h1...Picture005.jpg
Trimmed
http://i64.photobucket.com/albums/h1...Picture006.jpg
Lights off
http://i64.photobucket.com/albums/h1...Picture007.jpg
Lights on