what i have done for large openings is find a small rubber tube (ie windshield washer hose, vacuum hose, etc) and cut a slit in it. Then you can slip it over the metal edge and protect it. Can also spray some headliner adhesive to the inside of the tube to keep in place for extra insurance.
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565 twin 80mm 67 Firebird
545ci FFR MKIII Roadster
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