If a box was made by multiple people, there are a set of six "front-matter" cards that introduce the box (see example below). These aren't included in the card # total that you are charged (e.g. 25-card box, 50-card box, etc.)
The last one (in light blue) is an Introductory-Message Card. We haven't added the ability to change or customize the message or this set of designs for front-matter cards yet, although we have that on our product roadmap.
Front & Back of Introductory-Message Card (example):
If you are completing an AwesomeBox alone, the Introductory-Message Card will look and read like the following example: