See the Candles Chapter for more instructions, hints, tips, and ideas.
Since wax is lighter than water, it will float. Floating candles are usually small fancy shapes that are placed in a shallow bowl of water. They can be made using molds like ice cube trays, candy molds, muffin tins, or small paper cups. The candle needs to be much wider than tall to keep it from tipping over.
You will probably want to use a colored wax so the candle is more visible while floating on the water. As an alternative, add a few drops of food coloring to the water.
You can also make them using cookie cutters. For instructions, see the page on stacked candles.