The countdown timer is an application running on smartphones with a countdown machine. Couples put their smartphone together and each smartphone shows a half of a "knob." Couples rotate the knob together to set up the countdown time for their next important joint events in the future. The countdown machine than starts the countdown and displays a sand timer that flows slowly. The machine imitates the sound of flowing sand. It starts with imperceptible volume and becomes louder when the end point is coming.
Reference: Kirk et al. 2016. Ritual Machines I & II: Making Technology at Home. CHI' 2016.
