To give the wall a canvas, painting-like quality, it's been covered in burlap, then plastered, then painted with a raindrop print reminiscent of something Magritte might have done. We love seeing this hard work come into fruition in the close-up shots. Just look at how much this looks like a painting:
For those interested in making a similar surface themselves, check out a very detailed (and entertaining) description from the folks who made it happen: Chroma Lab. There are lots more pictures on their site, too.
Images: Chroma Lab