The pattern would decide how much material can be used to craft the tool part, and will decide how strong tool part could potentially be.

Answer:
Currently, you have to register a new pattern with unique properties, and make it possible to craft this pattern, or make it available in treasure chests. Creating new patterns is extremely easy and creating a huge amount of variations of a pattern with unique properties is the way forward. I can then filter patterns based on their rarity, and make them appear in different treasure locations, or make them drop from enemies.