Not all boxes measure the same, so don't think if you don't come up with the same cuts that I did that you did something wrong. I'm sure you did fine...
Have you noticed all the pretty designs on tissue boxes in the stores these days? I have and some of those printed beauties I just can't bear to throw away. And we don't need to be adding something so pretty to a landfill. So I reuse them in this way. I cut them up and make ATC's or tags or even gift cards from the old boxes. Here's how I do it.
Step 1: Open up the box
Open up the box at the glued end so it is now laying flat. It should look like the picture.