1. Wash and dry shells. Cover work surface with waxed paper.
2. Place a small amount of each paint color on a disposable plate. You will use mostly iridescent white. Paint the entire shell iridescent white. While wet, add a touch of color to the painted shell. A tiny bit of intense color goes a long way on the white. Dip the tip of a brush into color and paint onto the shell. While still wet, clean brush and add another color in another area; subtly blend the colors together. Experiment with color combinations, such as pink and yellow, yellow and green, green and turquoise, turquoise and purple, and purple and pink. Add a third color or just paint solid. Let shells dry.
3. Mix about 1/2 teaspoon of fine white glitter into 1/2 cup of white sand.
4. To decorate glass bowl, paint the outside with a thick, even coat of decoupage medium. Using glue, glue some shells onto the side. Pour the glitter-sand mixture onto wet decoupage medium, and pour off excess. Repeat this process until covered. Let dry. To keep the sand in place, handle the bowl from the inside or the bottom.
5. Glue shells around the top rim. Let dry.
6. Fill the bowl with sand, sprinkle a little glitter on top, and insert candles in the center.
Note: Never leave burning candles unattended