"We here at OCAddiction have just posted a page with some full scale blowhole
templates in PDF file's. These things will make it MUCH easier for people
wanting to put a blowhole in their case. Simply print the template, and you
have an easy way to mark your holes and line everything up so you don't make
swiss cheese outta your case! This is much easier than trying to drill thru
the small holes in a fan and tearing up the fan! (Which I used to do!)"
FULL STORY @ OCADDICTION (http://www.ocaddiction.com/articles/fantemplates/)