Klemens Torggler's door is an invention based on rotating squares, The special construction makes it possible to move the door sideways without the use of tracks. This technical trick opens up new applications for the door.

An Airbus 380 prepares to land after its demonstration flight during the closing day of the Paris Air Show in Le Bourget, north of Paris, Sunday, June 21, 2015. Some 300,000 aviation professionals and spectators are expected at this weekends Paris Air Show, coming from around the world to make business deals and see dramatic displays of aeronautic prowess and the latest air and space technology. (AP Photo/Michel Euler)