This mod is an addon for Tabula which lets you export your models in the entity json model format for ThreeCore. If you use the "threecore:default" type there is not much you need to take care of, but if you plan to make armor models with the "threecore:biped" type, there a few things you need to take care of:
"disabled": ["head", "head_overlay", "chest", "chest_overlay", "right_arm", "right_arm_overlay", "left_arm", "left_arm_overlay", "right_leg", "right_leg_overlay", "left_leg", "left_leg_overlay"]