Presenting, "METROPOLIS" My tallest K'nex ball tower up to this date. * Building time * Oct '09 - Aug '10 Number of pieces: 29.873 * Dimensions * Width: 1.40 m Depth: 1.15 m Height: 2.40 m Weight: 48 kg Link to picture slideshow: http://www.instructables.com/id/Metropolis-a-Knex-Ball-Machine/ Instructions for most elements used in this ball machine can be found her