assets/flansmod/models/block/modern.json

{
"parent": "block/cube",
"textures":
{
"particle": "flansmod:blocks/ModernBoxSide",
"down": "flansmod:blocks/boxBottom",
"up": "flansmod:blocks/ModernBoxTop",
"north": "flansmod:blocks/ModernBoxSide",
"east": "flansmod:blocks/ModernBoxSide",
"south": "flansmod:blocks/ModernBoxSide",
"west": "flansmod:blocks/ModernBoxSide"
}
}

assets/flansmod/blockstates/modern.json

{ "variants": { "normal": { "model": "flansmod:modern" } } }

assets/flansmod/models/item/modern.json


{ "parent": "flansmod:block/modern", "display": { "thirdperson": { "rotation": [ 10, -45, 170 ], "translation": [ 0, 1.5, -2.75 ], "scale": [ 0.375, 0.375, 0.375 ] } } }

In BlockGunBox.java

GameRegistry.registerBlock(this, "modern");

In ClientProxy.java

Minecraft.getMinecraft().getRenderItem().getItemModelMesher().register(modern.item, 0, new ModelResourceLocation("flansmod:modern", "inventory"));