Classes item

ModItems class:

public class ModItems {
    public static final List<Item> ITEMS = new ArrayList<Item>();

    public static final Item WAND = new ItemBase("wand");
}

ItemBase class:

public class ItemBase extends Item implements IHasModel {
    public ItemBase(String name) {

        setUnlocalizedName(name);
        setRegistryName(name);
        setCreativeTab(CreativeTabs.COMBAT);

        ModItems.ITEMS.add(this);
    }

    @Override
    public void registerModels() {
        Main.proxy.registerItemRenderer(this, 0, "inventory");
    }
}

ClientProxy and CommonProxy classes respectively:

public class ClientProxy extends CommonProxy {
    public void registerItemRenderer(Item item, int meta, String id){
        ModelLoader.setCustomModelResourceLocation(item, meta, new ModelResourceLocation(item.getRegistryName(), id));
    }
}

public class CommonProxy {
    public void registerItemRenderer(Item item, int meta, String id){}
}


RegistryHandler class:

@Mod.EventBusSubscriber
public class RegistryHandler {
    @SubscribeEvent
    public static void onItemRegister(RegistryEvent.Register<Item> event) {
        event.getRegistry().registerAll(ModItems.ITEMS.toArray(new Item[0]));
    }

    @SubscribeEvent
    public static void onModelRegister(ModelRegistryEvent event) {
        for(Item item : ModItems.ITEMS){
            if(item instanceof IHasModel){
                ((IHasModel)item).registerModels();
            }
        }
    }
}