I decided to give this a shot.I did a gauge pod in my focus so this is only my second time working with fiberglass,some thing may be the hard way of doing it but it is just because of my lack of experience.
first remove the tail light and cover it with masking tape.this will protect the light from the resin

then cover that with aluminum foil.

dont worry about the wrinkles they wont matter.
next i waxed the foil with car wax(paste not liquid)to act like a mold release.
I cut out two fiberglass cloth patterns,you can use more but remember the more you use the stronger the cover will be but also thicker.
Now i mixed the resin and just kinda painted it on the fiberglass cloth


after letting it cure over night(longer if needed) you can pop the mold of the tail light.the foil comes off pretty easy.

then i laid the mold over the light and shined a flash light thru the back so i could trace the outline of each section.
Then I measured and cut hole using different size hole saws.
you could really do what ever style opening you wanted,i just wanted to keep with the round style of the reflectors in the rear bumper and the round fogs in the front.


thats as far as i got.next will be trim the rough edges and mix resin and body filler and apply then sand,prim,and paint.Not sure if i will paint all silver go with the cladding body line and do bottom black top silver.
i'll post more as i get more done