If you're talking about the writing implements:
* Pens: This is the most common and straightforward antonym.
* Pencils: Another writing tool that's not a quill.
* Typewriters: A mechanical device used for writing, which replaced quills in the past.
* Computers: Modern technology that has largely replaced handwritten writing.
If you're talking about the pointed feathers:
* Feathers: This is a broader term that includes all feathers, not just quills.
* Soft feathers: Quills are often hard and stiff, so this emphasizes a contrasting texture.
* Down: A soft, fluffy type of feather that's not a quill.
If you're talking about the spines of a porcupine:
* Hair: Porcupine quills are modified hairs, so this is a general antonym.
* Fur: Another broader term that refers to the covering on an animal.
Ultimately, the best antonym will depend on the specific context in which you're using the word "quills."