If you are looking to "create a piece" (such as a mod, a map, or a specific item) using these files, here is how you can approach it: 1. Identify the Contents
These are the textures or sprites. Use an image editor like GIMP or Photoshop to "create a piece" of art or a new skin.
Repack the files (or keep them in the designated /mods folder).
To create a new "piece" of equipment, you often need to copy an existing entry in a JSON file and rename it.