sample gulpfile, with assets in vendor/bower

gulpfile.js

var elixir = require('laravel-elixir');

/*
 |--------------------------------------------------------------------------
 | Elixir Asset Management
 |--------------------------------------------------------------------------
 |
 | Elixir provides a clean, fluent API for defining some basic Gulp tasks
 | for your Laravel application. By default, we are compiling the Sass
 | file for our application, as well as publishing vendor resources.
 |
 */

// bower dir
var vendorAssetsRoot = "vendor/bower";

/**
 * SASS
 */
elixir(function(mix) {
    mix.sass('custom.scss', 'public/assets/css/custom.css');
});

/**
 * STYLESHEETS
 */
elixir(function(mix){

    // styles
    mix.styles([
        // bootstrap
        "bootstrap/dist/css/bootstrap.css",

        // animate
        "animate.css/animate.css",

        // font awesome
        "font-awesome/css/font-awesome.css",

        // nprogress
        "nprogress/nprogress.css"

    ], "public/assets/css/libs.css", vendorAssetsRoot);
});

/**
 * STATIC ASSETS (COPY)
 */
elixir(function (mix) {
    // FONTS
    mix.copy(vendorAssetsRoot + '/font-awesome/fonts', 'public/assets/fonts');

    mix.copy(vendorAssetsRoot + '/bootstrap/fonts', 'public/assets/fonts');
});