Here is a rough step-by-step breakdown of the process I used in creating the helmet for my Dead Space 3 Advanced Engineering RIG. Everything was eyeballed from screenshots (what few I could find online) and the rest I pretty much took creative liberties with.
1. I went to GoodWill and shopped around for a child size helmet that I could use for this build. Why child size when I am very much an adult? Because helmets are full of safety foams and padding making the shell very large, and the only piece I want is the shell.
2. I pulled all of the comfort pads and the large insert of hard safety foam. As I mentioned, I am only interested in the shell. This now made the helmet that was too small for my head fit with room to spare. Had it been an adult helmet, the final product would have been absurdly large like many of the pepakura helmets you may have seen built around the interwebs.
3 & 4. I sealed the holes with aluminum tape inside of the helmet and then used filler for the tops which I later sanded down once it had set.
5. I took a clear face shield visor and pop riveted it to the helmet shell. I then cut and rough fit the face shield pieces with tape to make sure I had the dimensions right... because as I said, I am eyeballing everything.
6. Here you see all of the foam attached to the helmet. The foam is all EVA foam which can be purchased in thinner sheets at places like Joann's while the thick pieces (not used here) can be purchased at Harbor Freight in packages of 4 large sheets used as anti-fatigue mats. The helmet also has two random plastic pieces I pulled from other junk in my garage to form the rear section of the helm and allow for adding the foam over top that you can see here. You can also the damage and wear I burned into the foam with a soldering iron and various tips.
7. A view from the back of the helm. More damage burned in here.
8. After sealing the foam in PVA (Elmer's) glue and then spraying the whole thing in gray primer, I began the first coat of black paint, seen here. This is the base as I will be using metallic colors.
9. This is after going over the black with a few coats of an antique bronze, hammered copper, and normal bronze.
10. In this shot you can see I have removed the tape from the outside of the visors. The blue inside is actually painter's tape I had not removed yet. You can also see the silver I had hand painted on.
11. Here I went over the whole helmet with a black wash which I rubbed off in different ways as I went along in oreder to give the paint a worn, dirty metal look.
12. And lastly, I built an LED array which runs both above and beneath each visor slit with a second reflective visor behind them so I can see out but no one else can see in. At this point it is 95% completed. The rest of the work will be picking out small details with a brush and installing a jack so i can have a remote power source that will plug into the helmet and is easy enough to disconnect and reconnect every time I take the helmet off or put it back on.