I used one of the new Individual EZMount Stamps from Sheena Douglas, this one is Silhouette Grass. I colored directly onto the stamp with various colors and added water with a paint brush after I'd stamped onto watercolor cardstock. I added the rainbow freehand, also with a paint brush.
Finally, I added a Die'sire Beautiful Butterfly that I also colored with Spectrum Aquas and the sentiment. Boom, super easy...lots of drying time in between, though.