Here is a link you might find helpful as TOm did it on his 4* 40

Build a Cowl from Balsa

I like the cowl but was afraid to do it on my 4* 40.

May have to modify to your size and set up though. Sure Tom won't mind getting you going with advice. He is a great person as I have emailed him a few times too.

Direct link to article. Scroll down to BAlsa Cowl