We talk about interaction day in and day out. How are we interacting with objects, with technology, with each other. How about the interaction of the objects with each other? I want to experiment with this idea. Us playing with object that would react to each other or that will allow you to build and see what it will do.
I am proposing a series of shapes that are placed on a conductive surface that would have different properties such as having a propeller, having a lamp, having a tone or a sensor. When you place the shapes on the surface they will be activated. Some of them won't be activated unless you stack them on top of a particular shape.
To give an idea here is a sketch of the idea.