Knights of Ren "Rogue" Helmet, The Force Awakens Concept Art
The Knights of Ren make a brief, rain-soaked appearance in The Force Awakens when Rey sees a vision of them in her dream. The Force Awakens concept art book shows some of the character designs in more detail, including this particular knight, apparently called "Rogue" (dubbed "Grenade Face" by the Star Wars community).
This helmet reproduction, based on the concept art, is constructed entirely of EVA foam. To achieve the pitted metal effect on the dome, Creature Cast neoprene rubber was stippled on with a chip brush. The "leather" strip and neck guard are in fact foam, painted and stitched to appear like leather. The paints used on this project were all Nova Color acrylics. The orange checkered pattern on the face plate is not seen in the film, but it shows up in the concept art book as an alternate color scheme.