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.
I had the same question and Eric mentioned he got his from Amazon so I did the same. Here's what i ended up buying:
10 Pcs Stainless Steel 200x3mm Transmission Round Rod for RC Airplane