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.
Just printing mine out now, it strikes me that you could probably have something like just an endcap that goes in the connector on the end of rail 2 instead of a full rail 3. There's not really much of an advantage there over having a full 3rd rail, but I guess it keeps it more open for further adjustments, like if I decided for some reason that I wanted 2 rail 2s and a shotgun rail, I wouldn't have to do away with that whole rail 3, just the endcap.
Bit of a strange thought but I figured I might as well share it.