Welcome to the forums! Dont know if you saw this link here. The tools I used for cutting the holes are at the bottom of the page. Initially, I fitted fairly standard fan grills as can be seen in the first pictures, but I did design and have made the Apple grills shown later on in the article. One of the things to watch out for here, is that you don't place the holes where they may interfere with the power supply - when installing the fans. The only other advice I can give is take your time, when cutting the holes through the plastic top, there is no substitute for having the right tools. Good luck if you give this a go, don't forget to show us the results.