Hello Jude,
I think the idea of using a pipe cleaner across the helmet is a perfect method of creating ones own kaskett-helmets as used by british horse artillery.
How about using an ordinary construction workers helmet as a bases. They can be ordered from the DS. I don't know the ETN though, but you can find the helmet in different colours in 3275 for example.
I think this would make a terrific kaskett!
EsDoc