Put a 80mm blow hole in case. Was pretty easy with the right tools. I used a 3 inch hole saw blade and masking tape is a must. I was going to use a dremel but very glad I didn't. The cutting took about 20 secs and then did a little sanding to smooth the edges. The masking tape prevented any real rough edges and help catch some of the shavings.
FYI, aluminum goes everyway so you must clean it out. At first I used my gas leaf blower and then still had to use a damp cloth.
Hope this helps.