I just happened to come across something on the internet. It could be from a Bavarian caterpillar helmet. Here is an example: Open link: www.weitze.net
Wow, that could actually fit. Especially the holes in the lower area! It would be very unusual for East Frisia, but who knows. I'll keep an eye on it!
SondelSuechtig 16.5.2024
You could do some research in that direction. Otherwise, France would also be a possibility for the motif. But I don't know anything about their helmets