You can make a variety of discovery bottles for your toddler and preschooler using rice, glitter, marbles and many more ideas. Here are some ideas from pre-school play.
Animals hidden in shredded paper. Lots of twisting and turning of the bottle required to get the animals to appear.
Car in rice. We use this one to learn about the different parts of a car. Can you see the wheels / windows / lights / mirrors etc.
Cut up pipe cleaners. Use magnetic wands to draw the pipe cleaners up the side of the bottle