I was looking around the internet and saw this idea and wanted to pass it to you.
It was to embroider on paper but then you find something from your old cards and use material from there. You could use the blank back of a card because it is a little bit shiny. You could cut a circle or any other shape and place it on your new card and do an embroidery over the circle. It would still have shiny showing around your design and you might have used a dark color for your original card. what a great look that will have.
Sue