My dad built the old lou andrews aeromaster and we just put a saito 100 it as well. He built it with 4 ailerons on the top and bottom and fully sheeted the wings. It was sort of on the heavy side but still flew well with a saito 100. Anyway the pictures show the cowl he made by using an old pot for a mold to lay fiberglass in. He then took it out and cut openings for the motor to stick out.