This fibreglass 3/4 head cast of Freddy was taken from a mold of a screen-used dummy Freddy head.
This particular head (eyes closed, grimacing) can been seen when the souls start clawing their way out of Freddy's chest at the end of the film, and would have been made using a lifecast of Robert Englund in Freddy makeup.
Cleaned up and painted by me.
More from A Nightmare on Elm Street 4: The Dream Master (1988)