I felt compelled to play with the Field of Depth technique some more, and ended up with four additional cards with the butterfly theme. On this batch I used the same butterfly from the background as the focal image. I embellished with Opaline half pearls instead of metallic ribbon, and like the effect better. On one of the cards I used white gel pen instead of paper piercing the scallops.
As I was puttering about with this project, I had a light bulb moment! Why not use silver Encore metallic ink in place of Going Grey dye ink? Although I'm not sure the photo below does it justice, I'm quite pleased with the results. (As ever, click on the photo to enlarge it.)
I wouldn't mind making another dozen butterfly Field of Depth cards, but I imagine it would get pretty dull for my readers. I will definitely be experimenting with this technique again in the future, though.