To keep the easel cards standing, we added 3 snowballs. As you can see, they are multi colored... use your imagination. I find when placing something to keep the card standing, that I go slightly off-center and preferrably something with some height. That is why the snowballs are stacked.
What do you think you will try? I know that I will be making more of these myself, can't wait to see what they look like. :-)