I'm trying to figure out the best way to explain this but I'm going to do my best.

I'm trying to figure out how to make a "digital data box." That's the best name I can come up with for it. You see them a lot in futuristic/hi-tech FPSs in your UI. They're generally a little semi-transparent box with some sort of data floating in them. I've used the rectangle tool and turned down the opacity for it, but I just can't seem to get it to look exactly the way I want it to. Any help or suggestions would be greatly appreciated. If you have an idea but can't quite figure out what I'm trying to say, I'll do my best to explain it to you in another way.