You will need some bake hard polymer clay.
I got mine from Wholeport...you can get packs with a big variety of colors.
Roll clay into balls.
Use a hobby knife to cut edges off the circles.
Then cut a little notch in them to hold a place card,
business card or even a love note!
Bake them in the oven according to package directions.
Usually 275* F for 15 minutes for every quarter inch thick...
I baked mine for about 25 minutes.
Let them cool and use!
this marbled heart card holder.