From the Blair County Sheriff's Department files (report filed by Deputy Gerald Garr):
Item was found left on the porch of Mrs. Lyla Granger on the morning of October 30th, 1973. Mrs. Granger's 7 year old son, Timothy, was one of the victims of Elmer Wyatt Heddy last Halloween. The mask is constructed out of newspaper clippings pertaining to the mass killing, along with other seemingly random clippings. The face appears to have been modeled after a jack-o-lantern; this would align with Heddy's obsession with Halloween. It matches the style of other masks found in the Heddy residence last Halloween. It seems these masks acts as trophies; most serial killers like to keep mementos of their crimes. Elmer Heddy, however (if indeed that's who left the mask), seems to like to leave the masks where they can be found, acting as a calling card.
Special thanks to the Ed Perry estate for allowing me access to these files.