Search Structures[]
These are for finding items in Quests.
Materials Generators[]
These only require silver to produce Collectables.
Workshops[]
These require silver plus items from the materials generators and produce Collectables.
Craftworks aka Specials[]
These require Collectables as raw materials and make new Collectables. No silver is required except to upgrade.
Temples[]
These work all the time once you have them. They are, however, quite expensive to upgrade.