Reported on 03rd December 2010
(Warner Bros., 2009) Production made T-800 endoskull with flesh applied to the skull for CG reference. Constructed of solid vacumetalized cast resin and exhibits nearly all of the foam latex “flesh” stripped off to appear like severe battle damage and brain chip reservoir in top of skull. The solid resin neck vertebra has a sturdy aluminum rod mounted underneath and electronics present which illuminate the left eye (requires 9V battery).
This was used as reference material for ILM and if Schwarzenegger would have refused his likeness we would have got this instead of his face for more screen time.

Estimated Value $7,000 - $10,000 (in 2010)
This T-800 Arnold (reference material) Skull was part of an auction that was held by iCollector mid-December 2010.
This item SOLD at 2010 Dec 18 @ 20:34UTC-8 : PST