I just cut and finished a nice cowl last week, I like the other post used a manilla file folder as a template, once I had the hole locations where I wanted them I then traced it on my cowl. To cut the cowl I used a dremel tool cut off wheel for the straight cuts ( use the thick cut off wheel , the thin ones break) To do the rounded cuts or corners I used a very fine file or a dremel drum sander works well to radius the corners. The big key is cut less on the first cuts other wise you may make the holes or cuts to big. I start small and work my way up. Once satisfied with the cut , I sand the edges for a smooth finish, do a final test fit and then paint the cowl.

hope this helps

Meeka

Measure twice cut once.