I recently finished making a Russian hat for my son, the lining and edging around the brim were made out of a good quality, long pile (around 2 inches) sheep's skin. FWIW, the appearance is remarkably similar to the pictures you posted. This isn't my period, but it might be worth experimenting with sheep's skin.
The number of sauces at the feast is directly proportional to the length of your dags times the cost of the material. -Sliverwing's 4th Law of SCA Dynamics
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