How is it so light and yet so strong?

Using the same "first principles thinking" that the brilliant Elon Musk gives credit to for his many novel and groundbreaking innovations, we redesigned the chair.

In Physics, there is a concept called Area Moment of Inertia.  You don't have to understand the details to understand the concept.  Basically, it is a method of calculating the resistance to forces applied to different cross-section shapes to determine which will provide the greatest stength in a given application. This teaches us that under many common loading conditions, material that is further away from the center of gravity of the cross-section is far more effective than the material near the center of gravity. It explains why a popsicle stick can be easily broken when flat but when rotated up ninety degrees takes on suprising strength. It also explains the shape of I-beams, bicycle frames and just about everything else you see that was designed by an engineer.

How much more effective is material that is further away from the neutral axis?  A lot more.  The moment of inertia is a function of the cube of the distance "d".  This difference is so dramatic that it makes the material that is close to the neutral axis insignificant by comparison.

So, why not remove it then?  

The 9611-010C Chair is completeley hollow. 1.27Kg 

The 9611-010C Chair is completeley hollow. 1.27Kg 

You can learn more about the design approach by scrolling down here.