The face cast is made from clear vacuum-formed plastic in the likeness of Data.
Production made Data epidermal face mold like one seen in Doctor Noonian Soong’s lab in the Star Trek: TNG season one episode #114 “Datalore,” which aired the week of January 18, 1988. In this episode the Enterprise crew investigates the mystery surrounding the disappearance of an earth colony in the Omicron Theta star system 26 years earlier. While visiting Data's home planet, the away team discovers a laboratory containing android body parts, including this mold, and then Data’s brother, Lore. Unbeknownst to the crew, Lore gained revenge on the planet's inhabitants before being disassembled by unleashing a ravenous crystal entity onto the colonists. The face cast is made from clear vacuum-formed plastic in the likeness of Data. PropWorx Star Trek Auction Lot 102, June 4, 2011.