The only way to get advanced patterns is to find them in treasure chests and other loot. I need to map out which loot structures needs to filled with Forgero loot, as well as how their rarity will affect the chances of finding an item.

Patterns

Default patterns can be created with paper and any tool, I don't really need to fill advanced chests with this type of patterns.
I can segment certain chests into a rarity category, which will prevent lower level patterns from being put into higher level chests.

Chest locations

Different chests and structures will contain different loot, as well as different tiers of equipment.

Abandoned Mineshaft

• Pickaxehead, bindings, handles, and their patterns
• Medium level loot 10-50

End city

• All tool parts and their patterns
• Highest level loot: 50-100

Desert pyramid

• Shovel, swords, bindings, handles, and their patterns
• medium level loot: 20-60

Shipwreck treasure

• axes, swords, bindings, handles, and their patterns
• medium level loot: 20-60

ruined portal

• All tool parts, but only in gold
• medium level loot: 20-60

Simple dungeon

• All tool parts
• medium level loot: 0-30

Pillager

• Weapons and handles
• medium level loot: 0-30

Stronghold library

• All patterns
• High level loot: 40-80

Woodland mansion

• Weapons, and axes and their patterns
• High level loot: 20-80

Weaponsmith chests

• Weapons, and axes and their patterns
• High level loot: 0-60

Toolsmith chests

• Tools and their patterns
• High level loot: 0-60