web sights like this one have printable fan guilds to know where to cut into the glass.http://www.mnpctech.com/index.html
with the 80mm fans change them out to one larger fan. the smaller 80mm fans make a lot of noise. I would see if 200mm would look good as one fan on the side. with fan on plastic...want short screws and rubber spacer and washer. if you crank down to hard on the screws you snap the plastic.