Django, I think Paul used a jig saw and a router. We tried a number of different ways to do this, but my molds were no where as nice as his. Paul did custom metal fab for years, and is an all around great wrench. He works in wood and metal.
I use a vise for the body of the mold, then use some screw clamps across the top. Before I take it apart I use a clicker knife to cut the front edge flush against the mold, then when it's dry I sand the top edge to true it up. I've made a template out of cardboard to make sure my edges are all straight and the same size when I trim it out
Skeeter, that's a great carving job. The flower really pops!