How to Craft a Small Backpack and Upgrade It to a Large Backpack
Crafting the Small Backpack
Start with the Small Backpack. It is made through the usefulbackpacks:crafting_backpack recipe type, which means the backpack is assembled from a base container plus the backpack material rather than a plain shaped grid. Gather the ingredients shown in your recipe viewer for the Small Backpack, place them in the crafting grid, and take the finished Small Backpack.
Upgrading to Medium and Large
The Medium Backpack and Large Backpack follow the same usefulbackpacks:crafting_backpack process. To move up a tier, use your existing backpack as the base ingredient and add the required upgrade materials in the crafting grid. The result replaces the lower-tier backpack with the next size up, so you keep progressing instead of crafting from scratch.
Keep the chain in order: Small Backpack → Medium Backpack → Large Backpack. Each step consumes the previous backpack, so do not craft a second Small Backpack expecting to combine two of them — the recipe expects one backpack plus the tier materials.
Once you have a Large Backpack, that is the top storage tier among the three backpack items. If you want automatic sorting on top of storage, the next thing to add is a filter item, covered in the filter guides.