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.
Actually I have cloned and modified step file parts in Fusion 360 for another RepRap machine that I built from a box of parts and a step file. It was a friend's design he did several years ago. I don't remember having any problems, but they were pretty simple parts to extend and modify, so, YMMV?