I use 5-ply 2 mm thick Finnish plywood for templates. Metal, or other materials are excluded because of hotwire cutting technology.
Most of them are (core and tip) airfoils, planned and printed by "Profili-II" software, onto normal paper, and glued on.
Being a lazy man, outside curves are not jigsawed, but roughly cut by giant tailor scissor, and finished by band sanding machine.
I made myself the .8 mm dia drill from my dentist, for boring the many dozen holes for glass-headed pins...
See in "The bluefoam model, hor how to..." topic
Istvan