I know this has been around for awhile, but when I went to play with it, it took me awhile to assemble all the pieces, so I put together a blog post that explains it step-by-step for anyone else who wants to give it a try: http://www.gullicksonlaboratories.com/using-reprap-to-bring-minecraft-creations-to-real-life/
Originally shared by Jason Gullickson
http://www.youtube.com/watch?v=HbNt9hUaqv4&feature=autoshare