Ai Weiwei says: 'Posters of the Door Gods are traditionally placed at the entrance to every Chinese family's home to protect them from evil spirits. This includes details from art works I have made, such as Sunflower Seeds and Watermelon; and internet memes such as Caonima [the red-nosed llamas in the foreground, and the title of Ai's Gangnam Style parody]. The caonimas represent the spirit of defiance against internet censorship in China. Each Chinese New Year, I create a different poster of the gods for netizens to download and post on their doors. I would like to share this with Guardian readers.'