Externals are user made levels. They can be made with the Elasto Mania internal editor or an external editor. The game's popularity is largely thanks to external levels. There are probably several millions of such levels. Not even close to all externals gets into the Internet however, but a rather big (more than 50k levels) collection gathered by fans of the game can be found at Moposite's discussion board, Mopolauta. New externals are battled daily in Elma Online.