In Notion, you can create a relationship between an Inventory database and a Materials database using the "Relation" property type. This allows you to link specific items in your inventory to the materials used to create them.

I’ve created a relation between these databases for you. Now, for each item in your inventory, you can select the related materials from your Materials database.

This relation allows you to track and manage the materials used for each item in your inventory directly from the Inventory database. It can also help you quickly identify which items are affected if there's an issue with a particular material.