Just an interesting vid - Link Below - but the 'Black 2.0' paint should be rather useful inside scope's & other places within light-path etc,,,
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Where to source it from :
http://stuartsemple.com/project/blac...-art-material/
https://www.amazon.com/BLACK-2-0-mat.../dp/B0758GKKGZ
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Video Link :
https://www.youtube.com/watch?v=AaFdCvnV8PM