Use pincers on Leather pieces drop from mobs to get different letter fragments - first component in recipe. Twine - second component buy from leatherworker NPC.
Third component comes from Chests - random drop from mobs. Apprentice's Chest, Master's Chest etc. When you open those you get some random materials for professions you know.
Edit: Higher level materials can be used in recipe. Or you can use Vial of Retroform from NPC to downgrade them - usually increasing amount.