Move your mouse over any shulker box in your inventory.
By default, press and hold Shift to reveal the full preview window.
Manual edits can be made in /config/shulkerboxtooltip.json5 .
You can change settings so the preview is always visible without holding a key.
To see how this mod and other utility mods can improve your building experience, check out this overview:
Go to your mod list (using a mod like Mod Menu for Fabric), select ShulkerBoxTooltip, and click the gear icon .
If installed on a server, it can also provide previews for Ender Chests. ⚙️ Configuration & Customization
If you have many boxes, you can enable a compact view to save screen space.