did some work tonight. had a previous blunder of cutting a fan hole of incorrect dimensions in the incorrect place. after thinking through the suggestions and trying to figure out a path of the least hassle, i decided to go for a 120mm fan, instead of the 92mm fan i previously had in mind when doing the blunder.
Placing the fan was difficult since there was less than 140mm to work with. add to that the space i needed to leave for the Audio and USB jacks made it even more difficult.
as you can see its very close to the side of the cabinet
with the fan
age old trick, using nail polish to prevent rust forming on the newly cut edges
the scrapped portion. you can see how badly it was cut. to be honest, that was the first time with a rotary tool, and i was 17 years old back then. now i am 20
i have improved a lot. I did the final cut with the rotary itself. Only used a knife to clean up the edges from burrs.