Prototype Journey


The Challenge: find a battery with a long lifespan that is sleek and lightweight.

CUE’s battery had mandatory requirements to ensure the best experience for our customers: The battery must last at least 3 months on a single charge with a target of up to 6 months (for residential use). The battery could not obstruct people from using the handle, so it needed to be sleek and lightweight. The battery also needed to be easy to charge therefore we incorporated a flash USB lithium ion battery. We used molds of standard doorknobs and tested a variety of battery sizing and positioning. We found that the battery being below the handle made it easier to grab and allowed the door to shut properly. As a result, the battery we selected is the perfect combination of size and lifespan.

User Interface

The Challenge: design a light panel that everyone in the world can understand.

How do you create a user interface on a door handle that people from every culture can understand? Traffic lights were the clear choice; they are universal and people recognize the implied meaning of red, yellow and green. For the timer, we tested several variations for how to display CUE’s message. While some of these initial ideas were stylistically pleasing, they lacked clarity in displaying when the washroom was ready to use. Ultimately, we determined that the hourglass, which is also a universal symbol, was the perfect solution when combined with traffic light illuminations.


The Challenge: create a door handle that would look beautiful in any home.

The inspiration came from conducting hours of research, both online and in-store. To create CUE’s custom look, the team examined numerous door handle styles, compiled a collection of top designs, added Cory’s aesthetic preferences and sent consolidated feedback to CUE’s developers. We also incorporated a removable interchangeable faceplate for customization. Three designs were 3D-printed and presented to focus groups. This feedback led us to confidently choose the CUE design you see on Kickstarter.