I’ve done some nibbling, lots of filing and brazing. Here is what I have so far for my Star Destroyer computer chassis.
Filing, slow and steady. 
This file was just the right size for the notches I needed for the side channels 
Came out a bit rough. I actually redid this one. 
The nibbler works, just a lot of filing to do afterwards. 
Positioning for the 120mm holes. I used a cheap fan to get the right dimensions. 
I got some nice Corsair ML120 PRO LED to place back here. 
Actually worked better when I marked it and took it away. 
A little rough, needs some filing. 
Marking for filing. 
Might take it back a little more to get good circles. You won’t reall see any of this anyways… 
My wife holding the channel piece while I braze. 
Looking good, just like 4 more pieces to go! 
It actually fits! That is screwed in. Now I just need to test the other holes.
My Crazy Projects 