I just finished the cowl on this 40 size plane about a month ago. I took a chunk of white foam and tack glued it to the fire wall. Then I carved and sanded it to the shape and length that I wanted to match up with my spinner. After this I put a thin coat of Spackle on and finish sanded everything. I then searched my house high and low for something to protect the plane and cowl. After much searching my wife suggested to use something made out of latex, and it worked perfect. Protected my plane and cowl, and the cowl just popped right off when I was finished.

This was my first try and it worked very well for me.

Just my 2 cents.