Here's a great craft for toddlers from my aunt and cousin. It requires a lid from a margarine container (or I imagine that a yogurt lid would work too), a large amount of Elmer's glue, a piece of string or ribbon, and items to decorate the suncatcher.
First fill the container with Elmer's glue and decorate with shells, etc.
Let the glue dry completely. The glue dries clear and can be popped out of the lid.
With a sharp point make a hole in the suncatcher and put a string through it.
Hang it in front of a window and admire!