[humara]

post some pics if you can.
if the inner lens is cracked, you could open up 2 sets and swap.
if the outer "lens" is cracked, you would need to replace that whole piece with another donor. if you're talking about painting the silver that is on the inside of the outer cliear plastic piece, you're going to have to strip it off somehow first (obviously) since painting black over that would not show.
i managed to bake some clear lights to replace burnt inner lenses. not too difficult. you'll need to scrape out all of the sealant and replace with new permatex. the sealant they used never gets soft enough to reuse.