To Tomas Saraceno the plastic bag is a building block.
In Minneapolis' Blake School gymnasium, Saraceno and his friend Alberto Pesavento are creating a balloon, or perhaps more correctly adding to a balloon. The sound of swishing plastic being taped together never seems to stop.
They began their project 18 months ago in Milan, Italy. Saraceno wanted to make a floating sculpture. As they didn't have any money, they hit upon the idea of having people bring them old plastic bags to add to a solar balloon.
Saraceno says a solar balloon is as about as low-tech of a flying machine as you can get. It just uses the suns rays and a small fan to get it started.
"Basically there is a kind of propeller which introduces a little bit of air into the balloon [where it] gets warm and rises up," said Saraceno.
But they discovered when you involve lots and lots of people, it soon becomes more than just a balloon project.
"Everybody who takes part has his own ideas and this makes it kind of alive," said Saraceno.
When they took their balloon to Medellin, Columbia, they found not only did people want to add their own bags, they wanted to draw on them and scribble messages.
And so that's how it became an art museum.
"The collection is always the same size as the museum, because you brings some plastic bags and the museum just grows," laughed Saraceno.
And now what had become known as the Museo Aero Solar just kept growing at every stop. Alberto Pesavento runs down the list.
"And after Columbia, we went to Lyon in France, then in Switzerland and then in Albania in the streets. It was too windy too fly it, so we made this kind of flying carpet," Pesavento said.
They took the Museo to the United Arab Emirates, and most recently to Israel. Part of the work today is to repair holes ripped in the balloon when the wind pushed it into a building.
As Pesavento and Saraceno have traveled with the balloon, they have thought about its significance.
They arrived in Minnesota about a week ago and began working with Walker visitors to prepare bags to add to the Museo. Pesavento says he was approached by a man who was curious about the project.
"He asked me, 'Are you [an] artist? Is it art or is it science? What is it?' And I sometimes say just it is a voyage back-forward in time, because this is kind of the beginning of the flying experiments like the first flying machines, at the same time it's something very new," said Pesavento.
To put it another way, Pesavento and Saraceno see an aviation of the future, which includes transportation by solar powered balloons. So far, they have just been inflating their balloon, and holding it in place. But as it gets bigger, they want to fly. Tomas Saraceno says they are getting closer.
"Like three percent of all pollution on planet Earth is caused by airplanes," said Saraceno. "And basically this does not cost anything. And I think with a few more steps we will be able to lift a person in the air. And I think we are now around 60 kilograms power lift."
So just enough to lift a small adult. Originally Saraceno had hoped to inflate the Museo Aero Solar at the Walker tomorrow, and then take it out into the country and fly it, without a passenger on Sunday. The Federal Aviation Authority wasn't so keen, because of the possible danger to air traffic.
Now Saraceno and Pesavento are working with staff at the University of Minnesota's Department of Aeronautical Engineering to design a remote controlled device which would puncture the balloon should it become a problem. That may satisfy the FAA. The plan is to go out to the Badlands of South Dakota for testing next week.
Meanwhile the inflation will start early tomorrow morning. Walker Curator Yasmil Raymond says it will start at 7 a.m., and as long as the weather holds, visitors will be allowed to walk inside the inflating balloon.
"Now Tomas tells me that's probably going to last an hour or maybe two maximum, because if there wind then you can't hold the tethers," laughed Raymond.
And she says you don't want anyone flying inside the balloon, right? Well, not yet anyway.