Hi Kelly,
First, cover the spinner with ceran wrap. Place  it on flat surface and lay 2-3 layers of glass about 6-8” starting from the bottom. Basicaly you are reproducing the area of the spinner that needs cutting. Pop it off when cured.
Now you can cut loose holes in this this fiberglass piece to be able to slip it over the blades an fit to the spinner plate.
Than cover the root of each blade with duct tape. Lay some glass to cover the gaps between the fiberglass piece and the blades. Remove after cure. Slip the fiberglass piece over your aluminum spinner and you have a perfect template matching your prop..
Bulent

Thank you, Bulent.  I was just getting to fitting my $210 carbon fiber spinner that I got from Klaus.  Didn’t want to screw that up.  Of course with the composite spinner I could ‘patch’ the fit after cutting the spinner, but this may be a better way.

Al