MendelMax is a new RepRap 3d printer designed by Maxbots. It is a true reprap, using printed brackets, but instead of using threaded rod for the structural elements it uses inexpensive aluminum extrusions. This gives a huge increase in rigidity for a minimal extra cost (About $50 more than a standard Prusa when purchased from the recommended suppliers). The required extrusions are available world wide from a variety of suppliers.
In addition to greatly increased rigidity, this design is faster to assemble (probably 4 hours for most users), easier to print, and easier to hack on.
Full assembly instructions and parts lists are available at http://www.mendelmax.com (Not resolving yet, in the meantime, see http://www.kludgineering.com/tikiwiki/tiki-index.php?page=MendelMax).