How to Clone Existing Items Into Circular Slider On Beginning and End

How to Clone Existing Items Into Circular Slider On Beginning and End

Can you please take a look at  This Demo  let me know how I can clone items into the  ul  to make a  Circular Slider  list. as you can see I have this list as following code but I need to clone  first item (left slide) or last item (right slide) at   beginning  and end of the list.

  1. var item = $(".thumbnail").width();
  2. var paddT = $(".thumbnail").css('margin-left');
  3. item = item + 20;
  4. $(".leftslide").on("click", function () {
  5.     $(".list-inline").animate({
  6.         left: '-=' + item + 'px'
  7.     }, 300);
  8. });
  9. $(".rightslide").on("click", function () {
  10.     $(".list-inline").animate({
  11.         left: '+=' + item + 'px'
  12.     }, 300);
  13. }); 
Thanks.