PneuHaptic is a pneumatically-actuated arm-worn haptic interface. The system triggers a range of tactile sensations on the arm by alternately pressurizing and depressurizing a series of custom molded silicone chambers. We detail the implementation of our functional prototype and explore the possibilities for interaction enabled by the system. We built PneuHaptic to explore a new style of tactile stimulus. Our device is a wirelessly controlled armband composed of a series of compliant nodes. The node gently presses against the skin when swelling, and hangs loose when deflated. By actuating the nodes in different patterns several haptic cues are generated. In this paper, we focus on three sensations: tapping, holding, and tracing.