schlappen would be too big. Strung chicken feathers/hackle is what you want. You can buy small qty at any orvis store, you want minimum 6-7" as they will be the most supple.
You don't use the quill on the bottom. Bend the feathers and you'll see why.
If you need larger qty call Chichester or Swalef or Zucker. You can buy them by the pound but a pound nowadays is close to legalized rape. All the costume outfits for women to thank for this. They've driven the cost of feathers thru the roof.