Bloop said:
Compared to the pics of the Acme unfinished kit in your other thread, it looks somewhat similar in that it is too thick around the eyes.
I'm thinking it could have been a kit, but the fin broke and someone tried to make their own, which would explain the mismatched color on the interior top of the helmet trying to cover the replace/repair job to the fin. The cracked or scratched left eye lense also adds to the assumption that the helmet was treated roughly and damaged.
Also, could it be a recast that someone did, but they removed the fin to make it easier to cast, then sold it without the fin? Whatever the case, that fin doesn't seem to match the rest of the construction; it looks thinner and flatter than the contoured one in the Acme kit, almost like it's cut from sheet metal.