To use as a planter, simply punch some drainage holes in the Jell-O mold. Since the molds are so shallow, gravel is not needed to for the base. Just fill the mold with potting soil and shallow-rooted plants that won't be too crowded by the shallow container. Spreads gravel on top of the soil. Because of the small container's size, the plants will need watering daily.
Slip the mold around your picnic umbrella pole, and you have an instant—living—centerpiece!