For the person asking about a Dremel cutting tool.
I lost your email so I'm sending this as a separate email.
Go to website:
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an select your country. If it's the USA, the opening window shows a Dremel EX-Lock Metal disk cutting tool. This is the Best and Fastest cutting tool I've ever seen. I have one and it does a superb and accurate job of cutting. The 'Kit' comes with the locking shaft and several extra disks that you may never need.
Additional tools required for a 'clean' job are: A set of high speed drill bits (for corners). A pipe reamer (for increasing corners radii), sandpaper and a Dremel 'Cone Sander'.
These tools in combination, will help you in making very clean opening in the cowl.
Earl Scherzinger AMA #40329