I found these old outdoor placemats. They are a woven, rubber like material. I read in one of the parent magazines that you can cut these into different shapes and once wet they make fun and easy bath toys that stick to the sides of the tub.
I cut them into shapes for sorting, a puzzle, bears for pretend play, letters, numbers, etc. B loves them and I like the freedom to make them into whatever I want.
Craft foam works the same way and also makes fun and easy bath toys