I made one of these at a scrapbook store about a year ago. The one we did at the store didn't have card stock completely covering the back of the envelope. Basically, these are 3 envelopes that are adhered together by the flaps like an accordion. The last flap is tucked into the envelope. Then you stamp and decorate as you wish. For a nicer and complete look, I used card stock to cover the areas of the back of the envelope, I punched a notch with my small oval. I also stamped three inserts back and front. You can write notes or add photos on all the inserts and the outer part of the envelopes as well.
All Supplies Stampin' Up!: Stamps: Priceless, Polka Dots & Paisley, Card Stock: Pretty in Pink, Taken w/ Teal, Certainly Celery, So Saffron, Ink: Pretty in Pink, Taken w/ Teal, Certainly Celery, So Saffron, Designer Paper: Petals & Paisleys, Accs: Punches: Small Oval, Circles 1-3/8 & 1-1/4, Key Tag, Ice & Fire Rhinestone Brads, Envelopes