How to Model mast profile for motor pod

Hi, am beginning my build by making the motor pod for a foil assist and am having trouble getting an accurate profile of my north cf72 mast. I can get pretty close but not perfect (±0.5mm) and there are small gaps between the mast and the pod. I was wondering how close do actually need to get it and what methods other people have used to model mast profiles especially on tapered carbon masts?