Steampunk Predator Environment Helmet.
Cast in fibreglass, the raw bio comes with the edges trimmed, but nothing more. You will need to cut out the eyes with a dremel, and do a little further sanding before painting it. Finishing is done with a combination of waxes, metal rubs and airbrushing to get a weathered finish that is full of texture and detail. While the bio is cast thickly, it is still light enough to wear as part of a costume, at around 1kg (2lbs).
More details, pictures, and how to purchase at Skunkworks Props.