Schematics
From Wiki
When some creatures die there is a chance that they will drop Schematics. They allow you to craft things, like granite storage chests and other various items. Think of them kind of like tinker bods, you need at least 95 tinkering for a chance to craft an object from one.
Here's a page you may find useful about them
12 schematics Added *Spoilers*
Have fun finding them all!