Hi from Germany!Okay - this is what I know about eiderdown featherbeds: the feathers come from eiderdown ducks (Norway), and are the feathers that the ducks use in their nests. The feathers are harvested - about half stay in the nest to keep the eggs warm. That makes the feathers very expensive. You would also need a special, very densly woven cotton fabric to keep the feathers from poking through. I have never heard of anyone who attempted to make her own eiderdown featherbed! If I were you I would look for a specialty shop that makes featherbeds - and look in Europe, we still have featherbeds on our beds! And we quilters use quilts too.
Let me know if I can help you with more information!
Greetings from sunny Tyrol!