LightTank is a mixed-reality installation that augments a space frame structure with holographic line drawings. Using the anaglyph (red/cyan) stereo projection technique on transparent screens, the haptic-digital construction merges with its surrounding and blurs the boundaries between tactile and virtual. LightTank creates a communal immersive experience with an intimate responsiveness to its audience. The project was conceived by the arc/sec Lab for Digital Spatial Operations at the School of Architecture and Planning at the University of Auckland. Headed by Assoc. Prof. Uwe Rieger, the Lab explores real-time Reactive Architecture as a fusion of physical materiality and digital information. LightTank’s interface was developed in collaboration with the Augmented Human Lab at the Bio-Engineering Institute. Under the lead of Assoc. Prof. Suranga Nanayakkara, the AHLab focuses on creating enabling human-computer interfaces as natural extensions of our body, mind, and behavior.