Need some black mesh wires or something of the sort

Where to get black colored mesh wire to cover blowhole? I want something not so restrictive of airflow and looks very clean.

like a screen window? that would be at a hardware store or home improvment

SOmething a little more sturdy. I am going to be placing it on top of my case to cover the hole that I am going to make for my rad.

Go to Home Depot or Ace Hardware. Look around, they should have something like that for one reason or another.

For now I use a white mesh I painted black.
I had a large fan (room fan) that broke, so I just took its mesh.

Or make your own. Get high gauge wire and cut a lot of piece and then put em together in a nice pattern and apply a slight spray paint coating (will hold wires in place a tad).