I haven't seen the cowl on a Cloud Dancer yet, since the one I ordered has not arrived yet. But one thing I have found that helps get a smoother cut is to spread a little bit of thin CA on the inside of the cowl before you start grinding. I also use my dremel and the paper template method mentioned by John Norton. I find that the CA minamizes the number of loose and peeling fiber glass strands I end up with around my freshly cut cowling holes.

PS: If your looking for a good first plane to fly before the cloud dancer. Check out Kangke's Astro Trainer H-40. It's one of the only trainers I've seen with a semisymetric airfoil and a bolt down wing.