I could take a picture, but I think the following illustration will help you more.
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.imgur.com%2FJgbfqTy.png&t=663&c=ICi98Z7w9DxmzA)
This is a top down view of a standard rack case in which the blades can fit. The airflow shield is pretty simple, I reused the foam, but it could be some plastic as well.
I used two big fans that normally operate under 12V, but they do the job just as well under 5V with a bearable noise level.
I don't know whether I got my Push and Pull terminology right, but the arrows should make it clear. Correct me if I am wrong. And I am by all no means an expert, other people could have better solutions.