The Inventory is where you see the blocks you carry. You see the inventory by pressing E. There is four different entries on top. It looks like the Factory interface:
Inventory has a limitation of 1000 blocks. When drilling resources you can carry an unlimited amount. If you want to take items from Factory Outlet or Container, you need to clear up space to be able to pick it up.
The difference between the factory and the inventory, is that you can't produce . In top of the Inventory window you can chose the "show only available items" click box, and then only see what you have. If not chosen you also see blocks types you don't have. The two categories "Manufactured Blocks" and "Constructions" got sub-categories to select what you want to view from or choose "All" to view all items.
Blocks and constructions can be dragged and drop on the field and into the Quick Select bar in the side panel.
Filter allows to search for specific itims.