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.
It will probably make a lot more sense if I explain it. The metal handle is flipped around backwards, and then a small hole just big enough for a zip tie is drilled right on the end. The "motor mount" print slides on past the hole, then a zip tie placed through the hole, then the mount can't fall back off. Once the mount is on, you can slide the motors through the back, and then screw the extruder parts on from the front. Better picture here: