Sand the table to remove any old finish. Turn the tub upside down on the spot where you want it. Toward one end of the table is best, because it leaves plenty of work room. Draw a marker line around the edge of the tub.
Mark around the tub outline 1 inch inside it. Use the jigsaw to cut out around this second line. Sand the first line to remove it. Cut a quarter-sized hole in one end of the cut-out wood.
Paint the table as desired, using a paintbrush. If the table will be in the sun, also apply a coat of weatherproofing. Finish the cut-out piece of wood as well.
Set the tub in the cut-out hole. Fill with soil. The cut-out piece of wood set over the tub will protect any leftover soil from the elements and neighborhood cats. A second tub can be used, filled with ice, to keep drinks cold during a backyard party.