ive seen it done. and it looks terrible. fibreglass and e-tape.
id just buy grills there cheap if you look. but US are 5$ a pair so give it a shot.
i thought of doing it for while just didnt know how it would look...buti wouldnt use fiberglass, although i have access to fiberglass and plastic..
i thought of using epoxy to glue it and then just smooth it out...
ill give it a shot theres plenty of grills at the yard if i fuck it up lol