The Pattern Chest is used to hold Patterns and Casts. It will accept exclusively Patterns, metal Casts or clay casts. It does not accept duplicates. Storage space is endless as long as unique items are used. If it already contains an item it will not accept other categories until it's emptied. The chest can be collected without dropping its contents.
When the Pattern Chest is placed adjacent to the Part Builder, you may access the Chest from the Part Builder for easy access to the Patterns and/or Casts.