Have now discovered that the blanks were cut away from several points around the aperture, which seems fairly irreversible


I've noticed four lugs with holes in on the inside of the bumper around where the blanks were cut out. Can anyone tell me if these are threaded? I'm thinking of cutting my own blanks from acrylic sheet and using these four holes as fixing points, if they will take screws.
Has anyone else done this, or found an alternative way of blanking out the fog light bumper holes??