Importing and Exporting

All there is left to do is importing the model into Model Engine and exporting it into a resource pack.

IMPORTANT: Before exporting, make sure your model is NOT using Box UV. It will mess up the loading process.
You can uncheck this option by heading to Files/Project and select Per-face UV.

Importing

Importing Generic Project (Most common method)

Put your .bbmodel file (contains model, textures, and animations) into your plugins/ModelEngine/blueprints folder. That's it! That's why this is the recommended format to use.

Importing Bedrock Project (Depreciated / old method)

Put your .json file (model) into plugins/Model Engine/blueprints.

Put your .png file (texture) into plugins/ModelEngine/resource pack/assets/modelengine/textures/entity.

Put your .animation.json file (animations) into plugins/ModelEngine/animations.

Note: If your model is .geo.json, remove the .geo. This is because the png file name and the model file name want to match, and the .geo gets in the way.

Exporting

After importing everything into Model Engine, reload the plugin in game or through console with /meg reload models. This will make Model Engine assemble a resource pack located here:plugins/ModelEngine/resource pack containing all the necessary materials to view your creations in game. Its assets will need to be put into a new or preexisting resource pack and applied in order to be seen.

New Resource Pack

Download the plugins/ModelEngine/resource pack folder. In that folder, make a pack.mcmeta file with the following contents:

{
  "pack": {
    "pack_format": 6,
    "description": "Your text here"
  }
}

The pack_format value will change on which version you are playing on-

4 for versions 1.13 – 1.14.4
5 for versions 1.15 – 1.16.1
6 for versions 1.16.2 – 1.16.5
7 for versions 1.17+

Preexisting Resource Pack

If you wish to add it to a preexisting resource pack, drag assets/modelengine and assets/minecraft/models/item/leather_horse_armor.json into it in the corresponding spots.

If that resource pack has a leather_horse_armor.jsonfile already, open Model Engine's one and select from the first {"predicate": to the bottom excluding ]} and copy that. Then in the preexisting file, select before that first {"predicate": and paste. Add a comma after the last part of the paste.

Note: THIS WILL ONLY WORK IF THE CUSTOM MODEL DATA VALUES DO NOT OVERLAP. IF THEY DO, YOU WILL HAVE TO CHANGE THE PREEXISTING VALUES AND ADJUST ACCORDINGLY FOR ANY ITEMS USING THOSE CUSTOM MODEL DATA VALUES. IT'S SUGGESTED TO GIVE THEM VERY LARGE NUMBERS SO IF YOU ADD MORE MODEL ENGINE MOBS THIS PROBLEM WILL NOT HAPPEN AGAIN.

Result

You should have a working resource pack now! To see it working in game, make a mob or npc using the model or a player disguise as it.

Note: The mob in this gif is spawned through MythicMobs.