SP3X is a new type of three-dimensional interface for creating, modifying, and navigating volumetric data. It combines the intuitive and improvisational strengths of tangible interfaces with the visualization power of mixed reality. Users can create 3D models by defining cross sectional slices. Users wear a head-mounted display that allows them to see virtual objects, like the model they are creating, overlaid on the real world. Interaction takes place through a hexapod structure with six-degrees of freedom.
(Source: http://tangible.media.mit.edu/projects/sp3x/)