These were blue on white, curved rectangular signs, cloned from the "bangpae yeon" Korean paper kite wall hanging object, and saying things like "staff only", "emergency room", etc. ... In my game, they're in the corridors of my hospital and on the front of my library, only I must've trashed the recolor packages, as they've reverted back to the originals. Now I can't find where I downloaded the recolors from. Searched for "signs" (a logical strategy, one would think) without any luck. The image here is from Sims 4, possibly, but it looks pretty much the same (as the original object)

They used to be on Retail Sims, which closed down a while back.

Had the files in my downloads (plus a few bonus hospital recolors I made a while back in the same style, and a couple smaller versions of the kite, because it always annoyed me how large it was - so added those in, too).
They've been compressed, so smaller filesize than the originals.
https://simfileshare.net/download/3285714/

Retail SIms - makes sense! Thanks simmer22!