So, where are the robots? We've been told for 40 years already that they're coming soon. Very soon they'll be doing everything for us. They'll be cooking, cleaning, buying things, shopping, building. But they aren't here. Meanwhile, we have illegal immigrants doing all the work, but we don't have any robots.

The only way to make something cheaply today is to have it mass-produced. For example, you wear the same shoes as everyone else. If you had a fabber, you could custom-make shoes that perfectly fit your feet. Three-dimensional printing will help us move away from the mass consumption that is so deeply ingrained in our culture.

We tend to think of science as finding equations, like E=MC2, that are simple and elegant. But maybe some theories are complicated, and we can only find the simple ones.

When it costs you the same amount of manufacturing effort to make advanced robotic parts as it does to manufacture a paperweight, that really changes things in a profound way.