MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
You don't need anything too special to run your motors from the bottom. I should know, I have my Prusa 'the wrong way up'! However, I use some short NEMA17 motors - Z axis doesn't need much power anyway - an extra bar at the bottom for the motor mount, and the Sells Z-rod clamp at the top. Also, bars at the bottom need to go over the bottom vertex rod. See here: http://dl.dropbox.com/u/709557/Reprap/IMAG0106.jpghttp://dl.dropbox.com/u/709557...
At least I don't have to worry about pushing down on the extruder breaking the z-motor-couplings!