My first helmet was made with 2mm cardboard using WOF's templates, then the finished helmet was covered with wall putty and then sanded. The helmet was painted with oil based paints but isn't a masterpiece:
The second helmet was at small scale and I used the WOF templates combined with Rich D.'s stencils and my own for the dome and right ears. This was made with thin cardboard and finished with printed stencils:
My third helmet was made the same way, but this time I did my own helmet templates. I skipped the putty and paint part, instead I made my own stencils to fit the helmet templates and I glued the printed parts on the finished helmet: