This clever new carry-on is designed to open like a trunk

Picture this: You’re at the gate, shoes pinching after a long walk through the terminal, and you know you packed your flats. They’re right there, somewhere in your carry-on. But getting to them means hoisting the bag onto a bench, unzipping the clamshell, and watching your carefully packed clothes threaten to spill out onto the airport floor. By the time you’ve wrestled the bag back together, your flight is boarding.

It’s a scenario that has played out in airports for decades—because...