Hi Haircloud,
Lots of people use the plastic shaper that a unit comes on to make a template. Of course if this is your first time you don't have one. If you don't want to make a second template you can always trace the edge of your template so that you have the length, width, and front and back curvatures for your records. Since the lace is soft and pliable it conforms to the shape of the head. It's also a good idea to mark on the template where you want the crown and part (if you want those).
Regards,
John
http://toplace.com/