Beaver Fur Skin Patch
A patch of real beaver fur, which is naturally bouyant, and probably a bit waterproof, as it does not absorb water easily, making it ideal for dry flies, even tiny ones.
It has very fine hair in the under-dubbing, and useful guard hairs that can be used legs and tails.
Mix them together and you have a water resistant dubbing with the texture of hares ear from a mask.
If you want to extract the fine hair, use a fine dubbing rake
The Beaver Fur Skin Patch is about 2 inches square (50mm)
Video instructions on Tying the Beaver Caddis with Barry Ord Clarke