Buckets

public class ItemBucketBase extends UniversalBucket implements ItemMeshDefinition {
    protected String name;
    final protected ModelResourceLocation modelLocation;

    public ItemBucketBase(String name, CreativeTabs aTab, ModelResourceLocation modelLocation) {
        super(Fluid.BUCKET_VOLUME, new ItemStack(Items.BUCKET), false);

        this.name = name;
        this.modelLocation = modelLocation;

        SetNamesAndCreativeTabHelper.setNamesAndCreativeTab(this, name, aTab);

        //registration must be done last
        GameRegistry.register(this);
        FoundationsMod.proxy.registerCustomModel(this, this, this.modelLocation);
        OreDictionary.registerOre("ore" + Utilities.upperCaseFirstLetter(this.name), this);
    }

    @Override
    public ModelResourceLocation getModelLocation(ItemStack stack) {
        return modelLocation;
    }
}

// Where the proxy location just ensures that models aren't registered for server-side logic, and the client side proxy does the work of the ModelLoader.setBucketModelDefinition function:

public class ClientProxy extends CommonProxy {
    public void registerCustomModel(Item item, ItemMeshDefinition meshDefinition, ModelResourceLocation modelLocation)
    {
        ModelLoader.setCustomMeshDefinition(item, meshDefinition);
        ModelBakery.registerItemVariants(item, modelLocation);
    }
}

// Then I've initialized it like so:

//hardened stone buckets
hardenedStoneBucket = new ItemBucketBase("hardenedStoneBucket", CreativeTabs.MATERIALS,
    new ModelResourceLocation(new ResourceLocation(FoundationsMod.MODID, "hardenedStoneBucket"), "inventory"));