How do I unlock the metal category in Little Alchemy 2?

In Little Alchemy 2, the Metal category is not something you "unlock" in the traditional sense. Instead, you create the Metal element by combining specific ingredients. Here's how you can make Metal:

1. Start with Stone and Fire to create Metal.
- Stone can be made by combining Earth and Pressure.
- Fire is a basic element you start with or can create by combining Air and Energy.

Alternatively, you can also create Metal by combining Ore and Fire:
- Ore is made by combining Stone and Metal (but since you need Metal to make Ore, this is a circular reference and not helpful for the first creation of Metal).

Once you have Metal, it will be added to your collection, and you can use it to create other elements in the game. The Metal category will then be accessible as you continue to discover new combinations involving Metal.

If you're looking to track your progress, you can always check your encyclopedia to see which elements you've discovered and which ones are still missing. Good luck!