Then there's the epitrochoid curve system, which consists of a wheel and a curved track. The wheel moves along this track when the door is set in motion:

The triangle system might be the most mesmerizing. In it, the door is split into two halves. Each of those halves is split diagonally, too. The two orthogonal edges that meet in the middle are connected by a mounted to a track which, when put in motion, pull the triangles into a folded position—the weight of which pulls the main edges into position:

The screen system is a complex, large-scale partition: Mounted around a central rod affixed to the floor, two distinct "double rod" doors swing out to form a room-sized screen. Unfortunately, there's no video of this one yet—but check out the still shot:

Many of Torggler's doors mix and match pieces of each system, and there are all kinds of crazy experiments to be seen on his YouTube page. Check out this asymmetrical glass version:

Or another series of early prototypes:

We've reached out to Torggler to find out what he's working on next—but in the meantime, check out his website for more. [Klemens Torggler]