There are lots of materials at the beach to make your own musical instruments. To make a shaker, drop a mix of shells and pebbles into an empty plastic bottle. Try, too, making another with a few strips of seaweed and a sprinkling of sand. Commandeer your lunchbox for a drum, and find a stick or strand of seaweed to beat it. Collect a few pebbles, and drop them into a bucket, or stir them with a stick. Or add some water to the bucket for a whole new sound.