Item Type	Material
Usage	Forging Material
Rarity

Weapon forging material. Can be used to forge 4-star catalysts. Philosophers believe marble has the potential to be sculpted into a beautiful statue. Likewise, these billets have the potential to become something greater.

Prototype Northlander Catalyst Billet — Northlander Catalyst Billet

Usage: Weapon Forging

Previously known as Northlander Catalyst Prototype, this prototype material are used to forge 4 craftable weapon:

Where to Get Northlander Catalyst Billet?

Reward from Adventurer Handbook Chapter 4

You can get Northlander Catalyst Billet after completing all quest from Adventurer Handbook Chapter 4. From what I remember, this was around AR 20-21 after you unlock last Anemo Statue in Stormterror Lair (part of quest in Chapter 4)

Buy From Xingxi, Mingxing Jewelry in Liyue Harbor

Xingxi from Mingxing Jewely in Liyue Harbor selling some weapon prototype materials, which including Northlander Catalyst Billet. All weapon prototypes in her souvenir shop can be purchased with 225 Geo Sigil which can be collected during player journey across Liyue.

Other than Catalyst prototype, she also sell Bow Billet, Claymore Billet, and Polearm Billet.

Xingxi Owner of Mingxing Jewelry Can Be Found In Liyue Harbor

Xingxi Wares in Mingxing Jewelry Including Northlander Catalyst Prototype

Dropped From Weekly Bosses

Northlander Catalyst Billet also have a chance to drop from weekly boss fight.