These remind me of mandalas. We could get stones and do mandala zendoodle art on them, and then write a simple encouraging message on the back for baby girl. Make a nice fabric bag for her to keep them in.
White painted stones by Natasha Newton - These would make a nifty place card. Just hand your guests a business card with a matching design on it. Then they get to match the card to the rock at their place. They could then take the rock home as a keepsake.