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.
Gathering iron from beach sand should be easy. The challenging part would be dispersing them evenly in filament while keeping particle sizes small enough to not clog. Actually, now that I think of it beach sand wouldn't be the best due to the magnetite it usually contains. It would be hard to separate from iron, and that stuff would probably clump together in the melt zone and clog stuff up. Probably iron fillings would be your best bet.