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 added a link in the info to my Tinkercad page where I made the designs. You can create a free account and modify them there. I believe that you should be able to import the stl files into openscad if you want to use that to modify them.
I look forward to seeing what you come up with. I started making a base that held batteries and modifying for a micro motor. I plan to finish it after I complete my T-rex skeleton.