Manipulating 3D objects on a tabletop computer is inherently problematic. The flat surface of tabletop computers enable natural 2D interaction, but lack the additional dimension needed to intuitively facilitate 3D object manipulation. In this thesis I present TZee, a passive tangible widget that enables natural interactions with 3D objects by exploiting the lighting properties of diffuse illumination (DI) multi-touch tabletops. The Tangible User Interface (TUI), TZee is constructed from several pieces of stacked acrylic glass. The stacked glass enables TZee to channel the light emitted from the tabletop slightly higher above the surface without major light loss. This technique allows the tangible interface to transmit touches on the device to the tabletop without any supplementary power. TZee enables simple translation, rotation and scaling along the x, y, or z axes. This thesis discusses several important design considerations of TZee, demonstrated TZee’s value though several applications and a gesture design study.