bower.json

{
  "name": "iron-list-448",
  "private": true,
  "dependencies": {
    "iron-list": "polymerelements/iron-list#^2.0.0",
    "polymer": "polymer/polymer#^1.9",
    "paper-card": "polymerelements/paper-card#^2.0.0"
  },
  "resolutions": {
    "webcomponentsjs": "^0.7.24"
  }
}

index.html

<link rel="import" href="my-app.html">
<my-app></my-app>

my-app.html

<link rel="import" href="bower_components/polymer/polymer.html">
<link rel="import" href="bower_components/iron-list/iron-list.html">
<link rel="import" href="bower_components/paper-card/paper-card.html">

<dom-module id="my-app">
  <template>
    <iron-list id="listbox" items="[[data]]" as="item">
      <template>
        <paper-card heading="[[item.firstName]]" image="" elevation="1" animated-shadow="false">
          <div class="card-content"></div>
          <div class="card-actions"></div>
        </paper-card>
      </template>
    </iron-list>
  </template>

  <script>
    Polymer({
      is: 'my-app',

      properties: {
        data: {
          type: Object,
          value: () => [
            {"firstName":"John", "lastName":"Smith"},
            {"firstName":"Jane", "lastName":"Doe"}
          ]
        }
      }
    });
  </script>
</dom-module>