Types of Sponges
Buy new sponges or use ones that you have at home that haven't been used. Avoid sponges with abrasive bottoms. The best to use are large rectangular kitchen sponges that usually come in a pack of four, each being a different color. These are usually the most inexpensive as well. Avoid using sea sponges as they are difficult to shape into anything other than a ball and may be too rough for young children.
Sponge Shapes
Any kind of cookie cutter shape can be used to create interesting sponge bath toys. Use one rectangular sponge for each toy. Just place the cookie cutter on top, trace the shape with a pencil and cut it out with scissors. These work well for pre-school and kindergarten age children because the sponges will be small enough for them to handle and they'll be interested to figure out what each shape is.
Sponge Balls
You'll need about three rectangular sponges in different colors for this project. Cut each sponge up into four vertical strips; each will be about an inch thick. Begin laying strips on top of each other so they meet at the center but don't overlap anywhere else. The goal is to make a star burst shape. Keep adding strips to make the toy as big as you'd like. Once you have your desired star burst shape, secure the strips together with a small piece of wire. Trim the end of the wire so it's flush with the center of the sponge and no sharp edges are protruding.
Things You'll Need
To create the sponge balls, all you'll need is a pair of kitchen scissors and some plastic wire. If you don't have plastic wire in the house, you may be able to use ties for trash bags or even the ones that come with loaves of bread. Another option for securing the sponge strips is to use a bent paper clip. For the shapes, simply gather any cookie cutters you have already or purchase a few of them from a craft store. You'll need to have a pencil and a pair of scissors as well.