After workers filled the truck's bed with scrap copper, the men left the plant.
"They were pretty loaded -- it was squatting the truck," May said.
Workers told police that the only thing odd about the men was their hats, which differed in style from the hard hats everyone is required to wear inside the plant's gates.
"They said it was in the shape of a coal miner hat," May said.
A Constellium spokeswoman declined to comment on the theft.
May said plant security officers contacted several metal recyclers in West Virginia and surrounding states after the theft occurred Friday afternoon.
"It'll be hard to get rid of it," she said." If we get word out, all those recycling places aren't going to touch it."