[mindslight]

I was recently party to a conversation where someone was saying that they couldn't find eclipse glasses in the store, so they had to "look through a Ritz cracker, like they said on the news". I figured they meant use it as a pinhole lens, but they continued saying that the sun was still pretty bright even using the cracker. I didn't want to blow up the spot by clarifying/correcting (and it's not like I could have prevented their eye damage after the fact), but I definitely got the sense they were looking directly through the holes in the cracker. This person is an educated white-collar professional.

[stestagg]

This is amazing!, while I would never advise this as an option, it probably would be fine

[mindslight]

Erm, your comment makes me think you didn't quite get what I was saying.

Using the holes in a Ritz cracker as a pinhole lens to focus the sun on a sheet of paper seems eminently fine, as you're only subtracting sun from the case of looking at the paper outside (as opposed to using a glass lens to image the sun, which gathers light from more angles and concentrates it). It seems like poorer optical quality given its thickness, but could be handy if you don't have access to a piece of paper and a staple, or if you're a clickbait journalist trying to entertain a dying audience.

Looking through the hole is idiotic. It'll cut down on some of the light sure, but nowhere near the attenuation required - a quick search shows a #13 welding shade lets through about 10^-5 of the light.