The main, "core" piece was made out of some hobby wood from Michaels. This added stability to the prop but was still thin enough for my tastes. I traced the shape from my template out onto the board and then used my dremel to cut it out. I also sanded down the edges to even out the cuts and to bevel the blade's edge a bit.
The rest of the pieces are all foamies (even the giant screws!). These pieces were glued on with hotglue in layers to build it up.
One of the top pieces got stretched out and warped a little when I glued it down. I'll need to be a little more careful not to stretch craft foam pieces when I'm glueing them down next time.
The layers don't line up perfectly, so I'll need to finish the edges with something to smooth it out.