 The hardest part is understanding that you want to add so much functionality, but it's got to be almost transparent to the user. It can do this, but you don't need to know about it until you need it. So you can kind of maneuver. And this is exactly what we want people to do. Truong Fung is a designer and president at Uppa Baby near Boston, where they're not only creating products, but pushing their limits. It has to sit on this treadmill for about 40 hours continuous, and at the end of that, everything has to work.