Assorted Shulkers

Shulker boxes are added in tiers grouped into storage levels 0 to 5, with stone at the smallest end and netherite at the largest. Metals and gems such as tin, silver, steel, ruby, copper, iron, gold, diamond, emerald and amethyst join the list once the mod that adds them is present. Each box takes the same dye colors that a vanilla shulker box accepts, and the item tooltip displays the box's storage level.

To move a box one tier up, a player places the next material around it in a crafting grid, and the items already inside stay in place. Everything inside is kept when a box breaks, which matches how vanilla shulker boxes behave. Assorted Lib is required, and Fabric API is required on Fabric. Every player and the server need a copy of the mod. It is published for Fabric and NeoForge for 26.2, and the code is under the GNU General Public License v3.0 only, so it is open source.