Help -- Scratched the crap out of my case

I would just take the whole computer apart and use spray paint Or you can try touching it up with touch up paint that you get from an automotive store for cars.

The interior of the case or the exterior of the case?

How bad is the scratch? Pencil line thin or two inches wide and 4 inches long?

If it is just a pencil line thin scratch on the inside of the case go to a local hobby shop and get a small jar of black metal primer and a very fine thin brush. Two light coats should do it. Unless the interior is lit up like a Christmas tree it will not be noticeable.

If it is a small scratch on the exterior then it might be a bit more complicated. I'm thinking a coat of black primer and then a coat of matt black paint might do it.