I want to mask the black bars on my TV. Have you tried this?

[Warm Gun]

They stick out like a sore thumb depending on the disc and my TV's local dimming. Plenty of discs aren't well enough encoded for the letterboxes to be truly black. They drove me crazy yesterday. It's 65 inches. I imagine I'd need right mats and clips that only make it as far as the 8 mm bezels, so as not to damage the screen. One pair of mats for 1.66:1 and similar, one for 4:3 and similar, one for 1.85:1 and similar, and one for 2.39:1 and similar. Can't use the same ones for 4:3 and 1.66:1 because I don't want to block the tower speakers. If you've tried this, please recommend materials.