Scan the crowded wearables market, and you'll find a wild buffet of options. There are gizmos that wean you off cigarettes and monitor your sun exposure. There are wellness trackers of all sorts—and even some for pets.

No matter what the functionality, however, wrist-worn wearables haven't diverged much from the standard bangle-bracelet shape. It's often a matter of practicality—a simple cuff will fit on every wrist—but it means that devices are rarely a perfect fit. "When you create wearables, there's a lot of guesswork as to where the thing you're making touches the skin," says Madeline Gannon, a researcher at Autodesk.

How might we craft more personalized devices in the future? By removing the guesswork entirely. As Gannon puts it, "If you're going to be designing things for the body, why not just design them on the body?"

This sort of on-the-body modeling could let designers think beyond the bangle.

Gannon is exploring modeling techniques that use the human skin as their primary interface. Her prototype is called Tactum. Instead of creating free-floating models in software like CAD, Gannon's setup uses a Kinect camera and a projector to create a virtual modeling environment right on your hand.

The projector beams blue lights onto the skin. That light represents the base geometry of the band you'll eventually wear.