Create assetbundles in a specific folder

Hello,

My name is Ricardo and I have a question, how do I create an Assetbundle file for a specific folder? I can create an assetbundle of a certain extension (.fbx, 3ds, etc) but in a specific folder I can not think how. I’ll leave the code sample to create an asset bundle by an extension.

        //SAVE FBX FILES
    [MenuItem("Window/                               Save Specific Assets To Bundle")]
    public static void SaveSpecificAssets()
    {
        AssetBundleBuild build = new AssetBundleBuild();
        build.assetBundleName = "SpecificBundle";

        string[] files = AssetDatabase.GetAllAssetPaths();
        List<string> validFiles = new List<string>();
        foreach (string file in files)
        {
            if (file.EndsWith(".fbx")) validFiles.Add(file);
        }

        build.assetNames = validFiles.ToArray();

        BuildPipeline.BuildAssetBundles("Assets/AssetBundles", new AssetBundleBuild[1] { build }, BuildAssetBundleOptions.None, BuildTarget.StandaloneOSXUniversal);
    }

why is there no reply on this?