It took a while to get in the groove. My main tool is a surform which is a glorified cheese grater that you can see in pic 1 resting on the top.
I'm not sure exactly how this is going to work out although in Pic 2 a definite shape is forming. The bit added to the sides is giving a little extra curve. I suspect very little of this foam will be left in the end.
Pic 3 shows that I have a laser to help maintain the center line. I've just used it to draw a line now and again. Really this is freeform sculpture constrained by the canard and sides. You can also see a rubbish bin filled with foam. That was just from today.