By the way -- just to throw in some Arduino cred -- the piece pictured in the original post (all of receipts on the floor) was a piece I created for Spark 2009 in collaboration with Márton András Juhász http://nilseuropa.com/projects.htm and the Kitchen Budapest http://kibu.hu last year. It's called Murmur Study Murmur Study | Christopher Baker The 30 printers are controlled by some custom hardware we made and orchestrated by a few arduinos which are fed by Processing. The new version just plugs into the internet with an ethernet shield and skips processing and the computer.