We decided to go with Kisses instead of peanut butter cups, cause we just thought they were cuter. And we used white yarn, instead of string, cause we had yarn.
We cut one piece of yarn about 14" and the other about 9", tied them together so the ends were even and used low temp hot glue to glue the Kisses to the ends. We didn't bother covering the kisses with foil, the Kisses looked fine without it. We taped the other end of the yarn to the top of one small side of the candy box. We had pink paper so we cut two strips, 4" by 8.5" from each sheet, and taped the paper to the candy box.
The print out Family Fun provided is great, but if you want to do more than one, or 30 as is our case, it's a bit wasteful. So I made a couple of sheets, one with 24 of the keypads and the other with 28 of the screens. We just print them on white paper, cut them out, and glued them in place. K is going to write her name on the back of the box and they'll be all done. The end result is really cute.
Have fun and Happy Valentine's Day!