IIRC, the film used for LED displays was not only fairly monochromatic, but polarizing.? The idea was that light going through from the outside would be polarized, change polarization when bouncing off the inside, and then be blocked by the film.
Possibly you could combine both?
Harvey
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On 6/12/2024 11:16 PM, vk2bea via groups.io wrote:
What about rubylith tape (like we used to use to make PCB artwork)?
3M makes tape (which is pricey) but you can buy sheets for a few dollars.
