Millinery had its heyday in the 30s with the plants of Flechet in France and Borsalino in Italy. Their common point: the expertise around the making of the thinnest felts, from rabbit hair and others furs.
Pledge of quality
The tighter the felt, the more alive it will be and the more it will keep its shape. You need to pay attention to the finishing before judging the quality and the value of the hat. A thinner hat is more expensive and is worth the cost. Capacity to resist the rain without falling (be it through the density of the felt or a waterproofing treatment). Capacity of being folding and able to retake its shape. Capacity to resist to shrinkage.
Choosing the fur determines the watertightness of the felt, its brightness and its resilience in the finishing. There are dozens of types of fur from rabbit, beaver, hare, coypu, etc. Each fur has its own felting properties. Some parts of the fur, such as the back of the animals, are of a higher quality and require a higher price. Beaver is the best matter, but not always. It depends on what you're looking for on your hat. Fur is like a coffee seed. It must be of a great quality to produce a hat of an excellent quality.