What is the best way to cut holes in a MOBO tray?

I recently cut out some square holes in my motherboard tray so I could tuck some cables out of site behind the motherboard.

It was extremely hard also.

I tried a dremel tool. It was good for starting a hole but that was about it. Then I tried a regular saw with a jigsaw blade:

It was very hard to navigate but after a long time with a lot of sweat and muscle I got it done.

When I was done I took a file and filed it down then covered the edges of the square hole with electrical tape so wires would not get cut.

What is the best way to cut holes in a motherboard tray? What tools do you use? There has got to be a much easier way to do it than the way I did. My case was vibrating like crazy when I was trying to cut the holes.