I haven't reached the stage of spray templates as yet. But, as an engineer I am big on jigs.
I will be making my templates out of acetate sheet as used by overhead projectors. It is very cheap (everyone knows someone who works in an office). A dozen sheets of A4 will give you enough sheets to last a lifetime. They are very easy to cut with a sharp modellers knife.
They can be mounted onto curved frames made of stiff cardboard.
presumably, the lure is held in the same position each time by a clamp system of some sorts. If the free standing acetate frame has a couple of pointers, one for the nose, another for the tail, then the frame could be positioned in the same location every time, without error or hassle. the pointers don't touch the lure, just position both ends of the lure. Thus you control height, width, depth, distance and angle relative to the lure and gain repeatability without any effort.