Id like to add an elaborate plume arrangement on a helmet, dose anyone know how these were made.
Helmets always seem to have these strait tube like plume holders yet period images have really complicated feather arrangements with feathers in every direction(with attachment conveniently hidden behind the head). but if you put feathers in those strait holders you get a feather duster!

So is it historically plausible to use some other shaped holder ie: fan shaped to make a fan/birds tail shaped arrangement?

It's called a panache. It's just a simple cone, either cast or shaped sheet metal riveted into the back of the helm. The trick is to keep the feathers in. I've lost quite a few expensive ostrich feathers that way...

Matt

Some later helmets have a slot cut in the top of the bowl. This accepts a spring mechanism for a plume.

To keep my feathers in the correct position and to keep them from flying out, I've cut the pens to match the conical shape of the panache and wound them together with wax cord until the ensemble fits snugly. I've never lost feathers this way.