How I did it:1. Make the boxes. Decide what size you want your finished boxes to be. The bottom boxes of mine are 3.25"x3.25" and the top boxes are 2.5"x2.5". Purchase regular cardstock (I used white, but they could be any color), and cut it down to the appropriate size. For mine, this was 5.25"x5.25" and 4"x4" (the extra is for the sides of the boxes. Draw lines 1" from each side for the bottom boxes and 3/4" for the top boxes (or however high you want your sides to be), and score along the lines. (Scoring means that you're creasing the paper without cutting all the way through, it makes a nicer seam than folding.) You can use anything with a pointed tip to score. I used a large nail and a ruler. Make the lids to the boxes the same way. If you make them just a smidge bigger than the bases, they'll slide together nicely. Fold lightly along the score lines so you can see how tall the sides are for writing.
2. It's easiest to do the writing before assembling the boxes. I wrote "Something" on two sides of the top box. On the bottom box, I wrote one word on each side - "Old", "New", "Borrowed" and "Blue". I used a calligraphy pen, but I'm not a professional calligrapher or anything. If you really have bad handwriting, you could get vellum and print the words on it from your computer, then cut it and glue it on. Make sure to write the words on the lids of the boxes, not the bases.
3. Assemble the boxes. Cut the flap where the sides come together to create a tab. Fold the sides up along the score lines and fold the tabs in (as shown below). Use glue to attach the flap from the end to the inside of the side.
5. Tie ribbon around the boxes to hold them together. Your ribbon will cover the two blank sides of the top box, and two of the words on the bottom box. Vary which words show so your display looks better. This is also a good way to hide it if you didn't do a perfect job on some of your calligraphy!
6. Display. I used a cake pedestal and stacked all the favors, kind of like a Tiffany's display.