A mid-game inventory solution: The Toolbox! (or something like it)

I personally love the bundles and shulker boxes as inventory management, but an issue I'm running into is that bundles are very early-game, and shulker boxes are very late-game. I feel like both are very balanced with the difficulty to obtain them, but I'm running into issues with juggling tools.

So my idea is this: some sort of toolbox. It handles the things that wont stack into bundles, like shears and books and whatnot, but it isn't a whole portable chest. Something that only has a few slots, but just makes carrying around the myriad tools you need throughout the game a bit easier. I'm finding that once I start to get diamond gear, I'm taking a lot of tools with me out exploring, and that leaves less and less space for the cool items that I bring back. (And if I leave them, I somehow always find a case where I need a hoe of all things!)

I think that it should be obtained around the time that you start to get diamond gear, and should be balanced around that stage in the game. Maybe using diamonds in the crafting recipe, or even gold! I'd love to see gold getting the copper treatment and getting more use cases. 

All in all, I love the direction inventory management is taking, but I'm definitely feeling a gap in the middle stages of the game, and feel like something to manage my tools would help tremendously.