The cowling installation instructions call for the construction of an alignment spacer. This spacer is attached to the prop hub to which you then attach the cowling with drywall screws. During the trimming of the cowling it will be installed and removed many times, this alignment spacer ensures the cowling is installed the same way every time. The spacer is made out of 3/4 plywood and the builder is required to make a 5" cutout 4mm deep. I did this with a 5" sanding disc attached to my drill press. Very easy. Other than that there are just the holes for the prop hub & drywall screws to drill. The center hole for the prop hub pilot was cut with a hole saw.
