This image is my actual working diagram, the bottom number is the gap. The height of the bars were proportional.
After I had stitched the bars I sat and thought about their letters. At the beginning I had planned to stitch a border around the bars in the gap colour then back stitch the letters. I believe this will still work well if you don't have a program to design your letters.
For once I was well ahead of myself at this stage, the anniversary wasn't for another 2 months so I decided I had time to cross stitch the letters. Here I used the computer program.
This the actual graph in colour and symbol. The letters didn't exactly line up under their bars I needed to pay around with the spacing to get the right balance. This was probably the most time consuming part.
If you don't have a cross stitch program don't be put off from doing your own barcode, backstitching the letters will equally as effective. Have fun!