I used a hand saw to rough cut the mold to match the fuse. I just laid the saw flat and used minimal pressure, kind of just let it guide itself. I was dripping with sweat. It is hot and humid here, but if I did not want the wife to kill me I had to do that task outside. I had no proplem with the saw tracking, no grain in foam.
I cut both sides, , bottom and top. Gave it a rough sanding then transferred my alignment marks and lines.
I made a 1/4" ply disc that will be right behind the spinner. The engine down thrust is built into the firewall, so all I had to do was measure the length to the spinner, then transfer that to the cowl mold. Keeping the same distance top and bottom, that way the front will align to the spinner. I did have to angle the front for 2° right thrust.
I will cut out the spinner ring after I have classed the mold.
I have applied light spackling compound to the mold to smooth it out and fill imperfections.
A little more very light sanding and spackling, then it will be ready to seal with white glue.