Yeah it’s tricky to google this, because there are lots of different types CD cases. My super light amount of research seemed to indicate that they (mean the standard kinda brittle full height jewel cases that were super popular) are often polystyrene, is that what you found too? There are also very slim one, opaque ones, colored transparent ones, ones that look more like DVD cases (and are obviously made of different material), paper sleeves… CD case design had several life cycles.
If I remember correctly, generally speaking, polystyrene is a mess to laser, but I don’t think it’s ultimately hazardous if you’re careful? Like I’ve heard “melty and flamey”, but that is probably caveated with “if you’re hitting it hard”.
Definitely google a bit more on polystyrene laser safety, my half-baked memories aren’t to be 100% trusted here… but If it’s not outright chloriney I’d say it would be safe to try a light engrave at least, and see what you get? If I were trying it I might do it over a piece of waste material so that if it DOES melt, you don’t get melted plastic in your tray honeycomb.
If you give it a whirl, please post results, I’m curious! Good luck, and as with any new material, keep an eye on it in case it decides to get feisty.