You could also use Zatocoding, or superimposed codes (https://en.wikipedia.org/wiki/Superimposed_code) as a way to 'tag' cards.

For example, many research facilities kept a stack of edge-notched cards as a way to find papers to read. You write the name of a paper or book on a card, and you notch out the holes which correspond to a search term, like 'polymer', or 'cellulose' -- then you can use needles in those holes to search for them later.

You can also then do things like boolean searches. Let's say you want all of the papers which are about polymers which are not cellulose. First you poke the holes for 'polymer', and collect up all the ones that drop. Next you take that stack and poke the holes for cellulose -- the cards which drop are about cellulose, so you ignore those, and the ones left on the needles are about polymers which are not cellulose.

I got really into the idea of doing this as a way to do something like a crazed zettelkasten, and reading material from the time this was widely used they would claim they could sort through thousands of cards in a few minutes. Not as quick as ripgrep, but not too shabby.