Do It Yourself Projects

So I am having a beach wedding and I was thinking of ways to save money since the venue was SO expensive. I need help with DIY projects for the summer. I was thinking of forgetting floral centerpieces and going with large vases filled ½ way w/ sand and then putting small seashells, starfish, and sand dollars surrounding a large white candle. I was also thinking of a different variation of this same thing- sand, shells, starfish, but I was thinking about filling the vases with water and adding a Beta Fish and floating candles. Both designs would be set on a square shaped mirror w/ tea lights and starfish. Any other ideas for beach or summer themed weddings??