Pick an elephant ear from your garden. You will want one that has veins that are highly visible and that has no holes or rips in it. Cut the stem as close as you can to the leaf with your garden shears.
Pile the sand into a dome shape. This will be the inverse shape of your bird bath. In other words, the height of your sand dome will be the depth of your birdbath, so take care to make the pile even and smooth. Cover the sand with Saran plastic wrap.
Place the elephant ear where you would like it to be on the pile of sand. Remember that where you place it is where the imprint of the elephant ear is on the inside of your birdbath bowl.
Pour cement onto the center of the elephant ear. Smooth out the cement around the edges of the leaf. The farther along the dome you smooth the cement, the larger the bowl will be. For a bowl with just the elephant ear as the bowl, smooth cement only on the elephant ear and just an inch or so beyond it.
Cut and place a quarter-inch wide strip of cardboard around the edges. This will form an edge to your birdbath. You can lay the cardboard close to the edges of the leaf, or you can lay it towards the bottom of your sand pile.
Cement the cardboard down to make a ledge for your birdbath. Blend the cement around the cardboard and pay attention to any special blending that may be needed between the elephant ear and cardboard.
Place additional plastic wrap around the cement and sand pile and leave to dry for 48 hours.
Pull the Saran wrap off of the elephant ear and rim and set on a pedestal for a one-of-a-kind bird bath.