We’re stuck in an awkward spot. We can manufacture nearly any 3-D product we’d like. But these objects are trapped behind the 2-D computer screen we design them in.

One solution is to 3-D print a plastic mock up. A more efficient solution is a new working concept called Gravity Sketch. It’s essentially a 3-D notebook. You put on a pair of video glasses, grab the stylus, and hold a tablet in your hand. Then you draw your creation in 3-D space using augmented reality–the glasses, pen, and tablet work in concert to create a digital illusion that your drawing is floating right there in front of you. But you’re literally drawing on a 2-D surface.

The Gravity Sketch team refused to get into technical details about their system unless we signed an NDA, but they did share quite a bit more about how they designed the sensation of drawing itself. In fact, they may have solved one of the biggest problems in 3-D drawing today–namely, how do you make it feel natural to people who’ve grown up drawing on flat, 2-D surfaces?

Current 3-D drawing systems, including the holographic zSpace or this 3-D-printer pen, ask you to be part sculptor, part surgeon as you draw wisps in boundless midair. It’s a weird concept to get accustomed to.

Gravity Sketch takes a different approach. It only lets you draw on the flat plain of the tablet itself. But you work with your design in 3-D as you draw–and the program give you a set of rules by which to manipulate your design. “By providing a simple set of rules, people quickly learn the limitations of the tool and work their way around them,” the team explains. “Through experiments, we found that people could build their ideas out in a three-dimensional space while playing to their natural instincts and the ease of drawing in two dimensions.”

Here’s how it works. You draw something on the tablet. That drawing becomes, conceptually speaking, several pieces of paper stacked into a cube. You can then rotate or excavate those layers via simple controls on the tablet.

The value of this technique emerged during trial and error during the research process. Gravity Sketch tried out several low-tech inventions to simulate the experience of drawing in 3-D. The most successful, they decided, was a layered acrylic cube, so that’s what they settled on when they built the program.