"Extended crafting rules and a lot of magical items!"
- Treasure themes discuss different kinds of treasure--arcana, gems, relics, implements, armaments, etc.
- You can craft potions and scrolls in the Player's Handbook.
- The Dungeon Master's Guide expands that to other magical items.
- Uses tools proficiencies and Arcana proficiency and the spells you know.
- You can craft any magical item in the DMG, as long as it's not an artifact.
Magic items can also have randomly determined histories and creators. Creators include species and creature types--a dwarf, an aberration, a giant, and so on. Histories include being part of a religion, a symbol of power, something sinister, a prophecy, and more. Magic items also get minor properties and quirks, to round them out.