You will need:
Autodesk Inventor or another 3D modeling software that you are comfortable with.
Note: The original head model was from http://www.3dcontentcentral.com , which I then converted to an .ipt, and then rebuilt using work-planes and than making it into an amplifier with space to put a device in. The original model was just a solid head. The instructable shows you how to make turn it from a head into a fancy device amplifier :)