This was probably the most complex interactive I ever constructed. (I say “was” insofar as it was removed to make way for “The Hall of Human Life”.)
This exhibit contained two activities: one in which the visitor is guided through the construction of a PER3 molecule, and a navigable camera which the visitors could use to get a close-up look at live fruit flies.
Point of interest: the weird gizmo you see in the third frame is the mechanism that controls the camera.
For an extensive technical description, please visit Machina Designs.