Advanced Inventory allows you to upgrade your inventory with up to six areas that consist of 9 slots each. In addition to that, you can add functionality to them by adding special items like filters or crafters to them.
The mod is still in an early stage, so be sure to see more features soon.
To get started you need to craft an inventory upgrade and put it in the slot below the crafting area. You can open the advanced inventory using the 'R' key.
1.9 versions require CXLibrary
You are allowed to include the mod in a modpack if you give visible credit to me (CubeX2).