You could make it like a hot tub. Awesome Forget the plastic variety, here's the ultimate kiddie pool: A galvanized stock tank that can be kept cool or warmed with a pump that circulates water through a coil on the grill.
This pretty tulip card is tied with a bow. Once untied it opens up to reveal your message to Mom. Would be cute to write all the different reasons you love your Mom and do a whole bouquet of flowers in a vase!