Start off by creating a skeleton of the head piece. Keep the dimensions as small as possible (keep as flush to your head as possible, this helps in maintaining the proportions of the entire suit easier).
Next, add on the chin piece.
Next comes with headlight and forehead emblem.
Add the antennae.
Then the side pieces.
To fill in the cranial portion of the helmet, a two craft foam construction helmets were used.
First, transcribe the entire head onto craft foam. Use one of the craft foam helmets for the white side of the cranial, and one for the front (red) side of the cranial.
Add the antenna. Use PVC or foamboard for the antenna and emblem, as it is much stiffer material.
Next, the side of the helmet is made. The side is made out of layers of EVA foam and covered in white construction paper. The side antennas are made out of foamboard.
Add the headlight piece. I made it out of cardboard to maintain stiffness.
Completed head piece.