title: Angular CLI custom builder
body: <p>Angular CLI 6 introduced a new concept of builders (aka Architect Targets).<br>
  There are a couple of <a href="https://github.com/angular/angular-cli/tree/master/packages/angular_devkit/build_angular/src" rel="noreferrer">prebuilt builders</a> that come with <a href="https://www.npmjs.com/package/@angular-devkit/build-angular" rel="noreferrer"><code>@angular-devkit/build_angular</code></a>, but unfortunately there is no documentation that explains how to create your own builder.  </p>
  
  <p>How do I create my own builder (for example to modify the underlying webpack configuration)?</p>