I got a Corsair 5000D airflow case from a friend for free but it is missing all the four screws that hold the side panels on the back. All the screws I can find on the internet are the short version that don't have enough reach.
This screw is from my own PC case.
Edit: image with the short version that I was talking about
If this doesn't work, you can go with these and use nail polish to paint them black. It's a different head shape, but the Corsair ones are unique to them. (The tip may need to be filed off.)
https://www.mcmaster.com/91035A330