Ball of fabric. (if you wanted green/blue on tables) Group together fabric-covered balls to make a great filler for a bowl, a glass vase, or a basket. Cut fabric strips from coordinating fabrics and use glue to adhere the strips to plastic-foam balls.
DIY Spray Shells Silver spray all of those leftover shells with silver spray paint and you have an expensive looking decorative item. This would be awesome to do with gold spraypaint and include it in the centerpieces somehow!