This is how we did it back when I was starting out...
I first did it with pencil and paper, then eventually a computer, and finally a piece of 3d modeling software that would generate any pipe template configuration you could imagine. if you have any rudimentary drafting ability, or even want to learn for that matter, you can do this with a straight edge, scale (ruler), compass, and calculator. A t-square and adjustable triangle would really make it easy.
or, if you can use any CAD software, (you can download lots of free stuff) you can do it and print out the results to scale.
Basically, you draw a circle of the diameter of your pipe divided into 15 degree wedges, and an elevation view with the correct cut angle, you can project those across a set of equally spaced segments that match the diameter of the pipe. cut on the wavy line, and you're ready to mark the pipe.
A little google can probably find an online tutorial.