3D-printing is awesome, but it has its limits. For the time being, we mostly get static plastic figures, and while resolution is getting better all the time, we're far from a real replicator future. A new development is bringing us one step closer, however: printable optics.
A paper recently published by Disney Research—the folks who brought you the plant-computer interface—describes how certain techniques could lead to 3D-printed objects that respond to touch and manipulation with a lights. The simplest technique basically involves bottom-lighting a figure, and using specially printed "Light Pipes" to direct the light to the surface where you want a display.