Making a Sweet Sixteen Candle Ceremony Display?

I want to make a Sweet Sixteen Candle Ceremony display. I would like to use 4, 6, 8, and 10 inch by 2 inch thick candles. My idea is to space the candle out on a round board, we want a beach theme, so we would cover with sand and hibiscus flowers and shells. Any ideas on how to put it together so it would look somewhat like a sandcastle?

By Kitty Gillott from Huntington, NY