When you go to the beach, one of the first things you do is make the greatest sand castle you can muster. Moats? No problem. Walls around the castle(s)? Easy. Doorways and actual bridges? Ok, given the density of sand, this one can be a little trickier, and will usually result in frustration and disappointment. That's unless you take a Stone Spray robot with you.
The Stone Spray project comes via three architects from the Institute for Advanced Architecture of Catalonia. It's a way of making detailed pieces of art out of sand, soil and other earthly materials. It consists of a 3D printer attached to a computer and an eco-friendly liquid spray system.
After you fill a container on the robot with material such as sand, you can control where the arm of the robot positions itself and set it "printing."
The robot sprays that sand along with the liquid – an additive made up of Polypavement – in order to hold the intricate designs the 3D printing bot is capable of creating. To make the art, though, each pattern goes through four stages on the computer: Rhine form, simulation, optimization, and the result.
As you can see, rather than the generic sand castle, you could achieve something that looks like the Sagrada Família in Barcelona (except your sand castle won't take 145 years to complete). However, it probably wouldn't be fun to get sand between you laptop keys, or to carry a robot around the beach.
You can read the thesis by the team on the Stone Spray project website, and check out lots of cool sculptures the bot's already made.