www.digiplayground.com but I didn't find this one, but if you go to her blog at www.jamielanedesigns.blogspot.com and contact her, she might give you the information to purchase this. As you see in this first picture, it is only 2 pieces. Just fold on the dotted lines.
www.digiplayground.com and it is called A2 Stationary Box on that site. This is a Samantha Walker design and the directions on how to put this together can be found at www.samanthaleewalker.blogspot.com/2013/08/silhouette-cutting-file-tutorial.html It was not hard at all. The pieces above is the base of the box.