That's a tool like this?
http://www.toolpeddler.com/960-01.htm
Dunno if it wil cut through steel, I don't think so...

something like http://www.project-ch701.net/ch701_t...cle_cutter.jpg

doesn't cut through regular (thick) metal cases, but it does cut through light aluminium (Lian-Li's)

for regular cases you either buy a "klokboor", or a circle cutter for bricks/stone. costs 7€ @ Gamma. I've tried it and I hated to work with it. on a good hand drill it was difficult to keep under control and I couldn't make it cut the circle nicely: with my other circle cutter it slowly sliced off layers. with the stone circle cutter I had to push it hard so it would scrape some off. the drill got often stuck and finally jammed. perhaps it would work out better with a drill press or a strong person :D

I don't think a circle cutter for stone isn't goint to do the trick.
A friend of mine made a blowhole of 80 mm with a "klokboor" and much, much oil. He said it went pretty good and the blowhole looks indeed very, very good! But he doesn't have one big enough for 119 mm fans. Maybe I'll buy a bigger one. I saw one at Delva's but it costs € 24 though.

But on the other hand, I'm thinking of trying it with a "wipzaag" and some good blades. The holes are big enough so maybe it will work. And if it doesn't succeed, I'll fix it with rectangular fan guards :)

Any idea where I can get rubber rings? Those rings like this guy used for his HD:

I went do Delva and Gamma (Yper) and Supra Bazar (Tielt) but they don't have them.
I want them because I want as less vibrations as possible when I mount my casefans and radiator + fans to my case.

Round rubber O rings at hardware stores.

go to a bicycle shop and ask for their leaky inner tires that they'll normally throw away.

good luck getting that in your hdd rack though :)

I don't think I can use those tires for my fans :)

But that's the problem, I can't find them at local hardware stores. Strange enough...