The user-centered design process helps ensure the requirements of the users are met throughout the development of a product or service. Universal design is an approach that makes sure that the needs of people with disabilities are incorporated. While many have suggested combining user-centered design and universal design, we demonstrate how it can be done in the development of prototypes and mobile apps for the Internet of Things. Applying the user-centered and universal design process allowed us to identify complex issues with user interaction that would not have been found only using accessibility guidelines. We recommend focusing on technical accessibility, performing user evaluations with persons with disabilities, and having an accessibility champion for advocating universal design issues throughout a project.