That's rad, man!
Carbon-Li was designed with some pretty serious watercooling in mind, not the least of which being the 240mm radiator that would be on the top front of the case. Of course, there wasn't a hole there...yet. Ediejo started off by using spray adhesive to attach a properly sized printout to the top of the case where the radiator would eventually sit.
He started the cuts with his drill press, making a hole large enough for the jigsaw blade to go through. Then, it was off to the races with the jigsaw.
First one hole, then the other...and Ediejo was left with just a couple slightly rough cuts.
After the basic cutting, it was time for filing. And filing. And a little more filing, just to make sure everything had a clean edge.
He then used the holes on the picture to line up and drill the mounting holes for the radiator and fans. Afterwards, a little lamp oil made short work of the paper that he had used as his guide. The bottle of paint thinner is actually an additional step, as Ediejo didn't need the paint job and so didn't mind if it came off - in fact, it was better that it did.
For some people reading this, you may wonder why we showed every step of this rather than moving on - but the idea of using a proper guide glued to the case is a nifty trick that many could learn from. It's a great way to not have those "D'OH!" moments when you realise that you've drilled a single hole about 1mm to the side of where it needed to be.