Flat
Peace
If you want to dry your horns you need to lay them flat. If they aren't flat they'll always be a little damp somewhere and you'll never have a moment's peace.
へい, ひょう, びょう
たい, ひら
None
Being flat isn't enough, so you cover the whole thing in hay (へい). Hay absorbs water, so you add a flat layer of it.