This is the trickiest part. Java models use a different JSON syntax than Bedrock.
Option A (Simple items): Ignore complex models. Use a flat 2D inventory icon. Bedrock will render it as a default item. how to convert jar to mcaddon portable
Option B (3D models): Open Blockbench.
While manual conversion works, there are tools and software that can simplify the process or validate your add-on: This is the trickiest part
The first legitimate step in converting a JAR to an MCADDON is to open the .jar with an archiver (e.g., 7-Zip) or decompiler (e.g., JD-GUI, CFR). The goal is not to understand the Java logic yet, but to extract all non-code assets: These assets are placed into the textures/ ,
These assets are placed into the textures/, models/, sounds/, and texts/ folders of the resource pack. This is the only part of conversion that can be partially automated.