The back is comprised of three motifs, filled out with over 1 letters and numbers. I chose my initials and the year the box was completed, arranged in a seemingly random fashion so that it would follow the layout of the other sides of the box.
Motif A is found on pages 12 and 16 and is worked 15 rows past the center line. For details on flipping mirrored motifs, see the lid layout overview video.
Motif B is found on pages 6, 7, 10 and 11
Motif C is found as a half motif on page 16. Work the full motif by reversing the chart but not repeating the center line, as discussed in the lid layout overview tutorial.
Please note on the counts that those represent rows, or squares on a chart, ie they are two threads. So nine would be 9 rows or 18 threads between reference points.
Full guideline counts can be found here, all images can be enlarged by clicking on them