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.
One thing I really want to do is try painting beach pebble rocks. I have collected so many pebbles which I use for my beach pebble keyrings but so far I have only drilled holes in them - I have never tried painting them.