You will need:
4,3" or 4" clay flowerpots (depending on the size of your candles)
4 matching clay saucers
Acrylic paints, stones, feathers, sea shells, etc.
To make the holders: Decorate each pot around the top edge with a representation of the Element. For example, you could paint the pot for "Water" blue, then glue seashells around the top edge; green with rocks for "Earth"; yellow with feathers for "Air", red with yellow flames (painted) for "Fire."
If you don't want to do much gluing, try a stylized representation of the Element around the top edge...a wavy line in blue for "Water," flowing, feathery yellow strokes for "Air," sharp triangular lines for "Fire," and square, boxy shapes for "Earth."
Let your imagination be your guide. After the pots have dried for 24 hours, you may wish to put a sealant over your painting, especially if it's to be used outside. Then place each pot in it's saucer, add a candle in the center and you're done!