I wish I could answer your specific question. My advice would be to get in some practice with template making, I put in quite a bit of time making my predator build and a lot of frustrating trial and error,im still learning but Im not afraid at this point to fail and experiment.
take some butcher paper, duct tape or whatevery think you can use to create some cheap templates. then use some duct tape and cardboard to flesh out your shapes.
if you fail do it again, you will only get faster and better and you have only wasted pennies worth of materials. and once you get it right then you will always get to keep the work to finalize into final templates for the foam.
I know its not what you are exactly looking for but I hope it is the encouragement you need.