Yes, exactly. The clay supports the entire prop... not just a single blade. I'm very sorry that my pictures don't show *exactly* what the clay should look like. I was in a bit of a hurry when I took those pictures, as I was just doing a mock-up. I'd already made the molds and figured some pictures would have been helpful.

You make the other mold half by popping off the outside "dams" and scouping out the clay. You want to get as much of the clay out as possible, without scrapingor removing the prop. Then use a bunch of wax and PVA over the whole thing. Clamp the dams back on and pour the other side.

Hope this helps,
David