Adding ducks in the game, which you can harvest feathers from.
- Feathers can be made into quills
- Feathers can also be used to make heavy stuff lighter
- Filling for pillows (don't know a good use for pillows yet, but just give me a moment and I'll think of some.)
Ducks live on water, and eat seaweed which can be made in waterpatches. (See my other idea thread about gardening ideas.
Oooh there should be squids living in the water too! Combine those with fishing, occasionally you can fish one up and it will give you raw ink, which can be processed into writing ink. You'll need additional stuff if you want to change the colour though.
Oh no wait, you should FEED the squid a certain colour thingy so it will give you raw [colour] ink instead... Oh so many possibilities...