I had to cut my own navpod, and it wasn't too difficult. You will see many suggestions for best cutting tool to use, but I just used a small drill bit for the pilot holes, larger bits for the corners and mounting holes, and a slow-speed jigsaw with fine teeth for the big cutout. The trick is to go slow so the plastic cuts, not melts.
Most important, measure carefully! There aren't many easy reference points or lines on these pods -- in fact, no straight lines to be found anywhere. I used lots of masking tape and right-angle squares to get the cutout properly centered and aligned.
Of course, when I installed it I discovered that the stainless posts weren't exactly spaced to match the channels in the navpod. They were only out by a fraction of an inch, but it is enough to make the pod very difficult to attach properly. I guess I need to take a heat gun or something to try to widen the channels in the pod. Funny
, the old navpod fit just fine...