Just make sure that both of the matching surfaces are as straight as possible. Follow the instructions from Great Planes to assemble it. I use Bondo Spot Putty to fill in the seams. When the Bondo has dryed, I sand it with some220 grit paper. I will then go over the entire cowl with 600 grit to get it ready for primer. When you make your cut outs do not leave any square corners. Make sure that they are all rounded off. Good Luck, Dave