I would have posted earlier, but I was still working on my costume up until a few hours before we had to leave for the Matsuricon.
Here are some photos of my iron helmet.
I made the entire helmet out of Foamies sheets (2mm for the horns and detailing and I believe 5mm for the helmet itself). I used several layers of acrylic paint to give it a well-worn look. I started with metallic silver. It was too light, so I mixed that paint with black to give it a darker color. I added yet another layer of silver/black paint using a spongy brush (that’s the technical term!) to give it more of a “worn” texture. I then applied some bronze paint with a spongy brush to give it a rusty effect. Some of the battle damage was created using clear packaging tape underneath the paint.
For the horns, I created the basic horn shape using newspaper and tape. I then cut strips of Foamies and super glued them around the news paper horns. I painted them a sort of off-white at first, but it was much too light, so I mixed white, brown, and yellow to make the tan color you see now. The horns are super glued onto the helmet.