Heavy Shulker Box

Combining a heavy core with a Shulker Box in a Smithing Table produces a Heavy Shulker Box. These have some extra functionalities, along with some drawbacks:

+ Heavy Shulker Boxes have an extra row for holding items, bringing their total to 36 stacks. This is a simple upgrade to storage capacity.

+ Heavy Shulker Boxes can be opened while in the player's inventory by shift right-clicking. This is by far the most important change and is intended to be a final endgame solution to the inventory management problem.

+ A Heavy Shulker Box placed on the ground will produce a comparator signal proportional to the number of items in the biggest stack, up to 15. For example, if it contains 6 poppies, 5 snowballs, and 2 breeze rods, it will output a value of 6. Single-stack items, such as a sword, count as 1.

- Heavy Shulker Boxes can't be stored in an ender chest. This keeps the original shulker box relevant, and incentivizes players to have two storage solutions - one carried on them and one in their ender chest.

- If a player is carrying more than 4 Heavy Shulker Boxes, they will receive a speed penalty. Hence the word "Heavy." This also disincentivizes players carrying 27 in their inventory and never needing to use other storage means like chests, barrels, etc.