The front of the head is more straight forward on what needs to be cut out. But I'll wait a day or two until I'm clear on this.
I asked the C-3P0 builders how I should proceed and was told to slowly trim away the extra material. So I cut it off and still have a little more to trim or file off later.
Then I cut out the mouth and used a pencil to mark where I need to cut out the eyes. This is a bit nerve racking to do with a razor blade. 1 wrong cut and you will nearly ruin the part.
These are the tools I used to work on the head. A pencil, razar blade, snips and a curved file. So now the eyes are roughly cut out. You'll need to very carefully widen the eye holes until the eye ring thingy just barely fits in with a bit of force. You don't want it sloppy, nor do you want to over cut the eye holes out of whack so its not a perfect circle.