Thanks guys for the prototype that I updated for my own needs : Generate markup in polymer, as dom-repeat was unable to perform this operation.
Tags for search engines :
Polymer Generation dynamically dynamic markup custom element dom-repeat dom repeat balise dynamique dynamiquement
http://jsbin.com/wiziyeteco/edit?html,output
<!doctype html>
<html>
<head>
  <title>polymer</title>
  <script src="https://rawgit.com/webcomponents/webcomponentsjs/master/webcomponents-lite.js"></script>
  <link rel="import" href="http://polygit.org/components/paper-button/paper-button.html">
</head>
<body>    
  <dom-module id="x-test">
    <template>
      <div id="container"></div>
    </template>
  </dom-module>
  <script>      
    Polymer({
      is: 'x-test', 
      ready: function() {  
        // Declare custom elements 
        var customElements = [
          {name:'paper-button', title:'A'},
          {name:'paper-button', title:'B'},
          {name:'paper-button', title:'C'},
          {name:'paper-button', title:'D'},
        ];
        // Declare auto-binding, as we are at the root HTML document
        var domBind = document.createElement('template', 'dom-bind');
        domBind.customElements = customElements;
        var domBindDocument = domBind.content.ownerDocument;
        // Declare custom elements 
        for (var i in domBind.customElements) {
          var item = domBind.customElements[i];
          var elem = domBindDocument.createElement(item.name);      
          elem.setAttribute('raised', 1);
          elem.innerHTML = item.title;        
          domBind.content.appendChild(elem);
        }
        // Append to #container
        this.$.container.appendChild(domBind);
      }
    });
  </script> 
  <x-test></x-test>
</body>
</html>